diff --git a/TODO.txt b/TODO.txt
index 6ff9e9c..2e153a2 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -17,14 +17,13 @@ Current issues:
 In binary quantification (hp, kindle, imdb) we used F1 in the minority class (which in kindle and hp happens to be the
 negative class). This is not covered in this new implementation, in which the binary case is not treated as such, but as
 an instance of single-label with 2 labels. Check
-Add classnames to LabelledCollection? This should improve visualization of reports
 Add automatic reindex of class labels in LabelledCollection (currently, class indexes should be ordered and with no gaps)
 OVR I believe is currently tied to aggregative methods. We should provide a general interface also for general quantifiers
 Currently, being "binary" only adds one checker; we should figure out how to impose the check to be automatically performed
+Add random seed management to support replicability (see temp_seed in util.py).
 
 Improvements:
 ==========================================
-Clarify whether QuaNet is an aggregative method or not.
 Explore the hyperparameter "number of bins" in HDy
 Rename EMQ to SLD ?
 Parallelize the kFCV in ACC and PACC?
diff --git a/quapy/classification/neural.py b/quapy/classification/neural.py
index 68a924e..afeb649 100644
--- a/quapy/classification/neural.py
+++ b/quapy/classification/neural.py
@@ -11,8 +11,8 @@ from torch.nn.utils.rnn import pad_sequence
 from tqdm import tqdm
 
 import quapy as qp
-from data import LabelledCollection
-from util import EarlyStop
+from quapy.data import LabelledCollection
+from quapy.util import EarlyStop
 
 
 class NeuralClassifierTrainer:
diff --git a/quapy/data/base.py b/quapy/data/base.py
index 6b2ddec..ffd7e31 100644
--- a/quapy/data/base.py
+++ b/quapy/data/base.py
@@ -2,40 +2,52 @@ import numpy as np
 from scipy.sparse import issparse
 from scipy.sparse import vstack
 from sklearn.model_selection import train_test_split, RepeatedStratifiedKFold
+
 from quapy.functional import artificial_prevalence_sampling, strprev
 
 
 class LabelledCollection:
+    '''
+    A LabelledCollection is a set of objects each with a label associated to it.
+    '''
 
-    def __init__(self, instances, labels, n_classes=None):
+    def __init__(self, instances, labels, classes_=None):
+        """
+        :param instances: list of objects
+        :param labels: list of labels, same length of instances
+        :param classes_: optional, list of classes from which labels are taken. When used, must contain the set of values used in labels.
+        """
         if issparse(instances):
             self.instances = instances
-        elif isinstance(instances, list) and len(instances)>0 and isinstance(instances[0], str):
+        elif isinstance(instances, list) and len(instances) > 0 and isinstance(instances[0], str):
             # lists of strings occupy too much as ndarrays (although python-objects add a heavy overload)
             self.instances = np.asarray(instances, dtype=object)
         else:
             self.instances = np.asarray(instances)
-        self.labels = np.asarray(labels, dtype=int)
+        self.labels = np.asarray(labels)
         n_docs = len(self)
-        if n_classes is None:
+        if classes_ is None:
             self.classes_ = np.unique(self.labels)
             self.classes_.sort()
         else:
-            self.classes_ = np.arange(n_classes)
-        self.index = {class_i: np.arange(n_docs)[self.labels == class_i] for class_i in self.classes_}
+            self.classes_ = np.unique(np.asarray(classes_))
+            self.classes_.sort()
+            if len(set(self.labels).difference(set(classes_))) > 0:
+                raise ValueError('labels contains values not included in classes_')
+        self.index = {class_: np.arange(n_docs)[self.labels == class_] for class_ in self.classes_}
 
     @classmethod
-    def load(cls, path:str, loader_func:callable):
+    def load(cls, path: str, loader_func: callable):
         return LabelledCollection(*loader_func(path))
 
     def __len__(self):
         return self.instances.shape[0]
 
     def prevalence(self):
-        return self.counts()/len(self)
+        return self.counts() / len(self)
 
     def counts(self):
-        return np.asarray([len(self.index[ci]) for ci in self.classes_])
+        return np.asarray([len(self.index[class_]) for class_ in self.classes_])
 
     @property
     def n_classes(self):
@@ -48,21 +60,21 @@ class LabelledCollection:
     def sampling_index(self, size, *prevs, shuffle=True):
         if len(prevs) == 0:  # no prevalence was indicated; returns an index for uniform sampling
             return np.random.choice(len(self), size, replace=False)
-        if len(prevs) == self.n_classes-1:
-            prevs = prevs + (1-sum(prevs),)
+        if len(prevs) == self.n_classes - 1:
+            prevs = prevs + (1 - sum(prevs),)
         assert len(prevs) == self.n_classes, 'unexpected number of prevalences'
         assert sum(prevs) == 1, f'prevalences ({prevs}) wrong range (sum={sum(prevs)})'
 
         taken = 0
         indexes_sample = []
-        for i, class_i in enumerate(self.classes_):
-            if i == self.n_classes-1:
+        for i, class_ in enumerate(self.classes_):
+            if i == self.n_classes - 1:
                 n_requested = size - taken
             else:
                 n_requested = int(size * prevs[i])
 
-            n_candidates = len(self.index[class_i])
-            index_sample = self.index[class_i][
+            n_candidates = len(self.index[class_])
+            index_sample = self.index[class_][
                 np.random.choice(n_candidates, size=n_requested, replace=(n_requested > n_candidates))
             ] if n_requested > 0 else []
 
@@ -90,21 +102,22 @@ class LabelledCollection:
     def sampling_from_index(self, index):
         documents = self.instances[index]
         labels = self.labels[index]
-        return LabelledCollection(documents, labels, n_classes=self.n_classes)
+        return LabelledCollection(documents, labels, classes_=self.classes_)
 
     def split_stratified(self, train_prop=0.6, random_state=None):
         # with temp_seed(42):
         tr_docs, te_docs, tr_labels, te_labels = \
-            train_test_split(self.instances, self.labels, train_size=train_prop, stratify=self.labels, random_state=random_state)
+            train_test_split(self.instances, self.labels, train_size=train_prop, stratify=self.labels,
+                             random_state=random_state)
         return LabelledCollection(tr_docs, tr_labels), LabelledCollection(te_docs, te_labels)
 
     def artificial_sampling_generator(self, sample_size, n_prevalences=101, repeats=1):
-        dimensions=self.n_classes
+        dimensions = self.n_classes
         for prevs in artificial_prevalence_sampling(dimensions, n_prevalences, repeats):
             yield self.sampling(sample_size, *prevs)
 
     def artificial_sampling_index_generator(self, sample_size, n_prevalences=101, repeats=1):
-        dimensions=self.n_classes
+        dimensions = self.n_classes
         for prevs in artificial_prevalence_sampling(dimensions, n_prevalences, repeats):
             yield self.sampling_index(sample_size, *prevs)
 
@@ -142,10 +155,10 @@ class LabelledCollection:
         else:
             nfeats = '?'
         stats_ = {'instances': ninstances,
-                'type': instance_type,
-                'features': nfeats,
-                'classes': self.n_classes,
-                'prevs': strprev(self.prevalence())}
+                  'type': instance_type,
+                  'features': nfeats,
+                  'classes': self.classes_,
+                  'prevs': strprev(self.prevalence())}
         if show:
             print(f'#instances={stats_["instances"]}, type={stats_["type"]}, #features={stats_["features"]}, '
                   f'#classes={stats_["classes"]}, prevs={stats_["prevs"]}')
@@ -155,13 +168,14 @@ class LabelledCollection:
         kf = RepeatedStratifiedKFold(n_splits=nfolds, n_repeats=nrepeats, random_state=random_state)
         for train_index, test_index in kf.split(*self.Xy):
             train = self.sampling_from_index(train_index)
-            test  = self.sampling_from_index(test_index)
+            test = self.sampling_from_index(test_index)
             yield train, test
 
+
 class Dataset:
 
     def __init__(self, training: LabelledCollection, test: LabelledCollection, vocabulary: dict = None, name=''):
-        assert training.n_classes == test.n_classes, 'incompatible labels in training and test collections'
+        assert set(training.classes_) == set(test.classes_), 'incompatible labels in training and test collections'
         self.training = training
         self.test = test
         self.vocabulary = vocabulary
@@ -171,6 +185,10 @@ class Dataset:
     def SplitStratified(cls, collection: LabelledCollection, train_size=0.6):
         return Dataset(*collection.split_stratified(train_prop=train_size))
 
+    @property
+    def classes_(self):
+        return self.training.classes_
+
     @property
     def n_classes(self):
         return self.training.n_classes
@@ -195,19 +213,15 @@ class Dataset:
         print(f'Dataset={self.name} #tr-instances={tr_stats["instances"]}, #te-instances={te_stats["instances"]}, '
               f'type={tr_stats["type"]}, #features={tr_stats["features"]}, #classes={tr_stats["classes"]}, '
               f'tr-prevs={tr_stats["prevs"]}, te-prevs={te_stats["prevs"]}')
-        return {'train': tr_stats ,'test':te_stats}
+        return {'train': tr_stats, 'test': te_stats}
 
     @classmethod
     def kFCV(cls, data: LabelledCollection, nfolds=5, nrepeats=1, random_state=0):
         for i, (train, test) in enumerate(data.kFCV(nfolds=nfolds, nrepeats=nrepeats, random_state=random_state)):
-            yield Dataset(train, test, name=f'fold {(i%nfolds)+1}/{nfolds} (round={(i//nfolds)+1})')
+            yield Dataset(train, test, name=f'fold {(i % nfolds) + 1}/{nfolds} (round={(i // nfolds) + 1})')
 
 
 def isbinary(data):
     if isinstance(data, Dataset) or isinstance(data, LabelledCollection):
         return data.binary
     return False
-
-
-
-
diff --git a/quapy/data/datasets.py b/quapy/data/datasets.py
index 79d0bbf..575ffca 100644
--- a/quapy/data/datasets.py
+++ b/quapy/data/datasets.py
@@ -47,7 +47,7 @@ UCI_DATASETS = ['acute.a', 'acute.b',
                 'yeast']
 
 
-def fetch_reviews(dataset_name, tfidf=False, min_df=None, data_home=None, pickle=False):
+def fetch_reviews(dataset_name, tfidf=False, min_df=None, data_home=None, pickle=False) -> Dataset:
     """
     Load a Reviews dataset as a Dataset instance, as used in:
     Esuli, A., Moreo, A., and Sebastiani, F. "A recurrent neural network for sentiment quantification."
@@ -91,7 +91,7 @@ def fetch_reviews(dataset_name, tfidf=False, min_df=None, data_home=None, pickle
     return data
 
 
-def fetch_twitter(dataset_name, for_model_selection=False, min_df=None, data_home=None, pickle=False):
+def fetch_twitter(dataset_name, for_model_selection=False, min_df=None, data_home=None, pickle=False) -> Dataset:
     """
     Load a Twitter dataset as a Dataset instance, as used in:
     Gao, W., Sebastiani, F.: From classification to quantification in tweet sentiment analysis.
@@ -162,12 +162,12 @@ def fetch_twitter(dataset_name, for_model_selection=False, min_df=None, data_hom
     return data
 
 
-def fetch_UCIDataset(dataset_name, data_home=None, test_split=0.3, verbose=False):
+def fetch_UCIDataset(dataset_name, data_home=None, test_split=0.3, verbose=False) -> Dataset:
     data = fetch_UCILabelledCollection(dataset_name, data_home, verbose)
     return Dataset(*data.split_stratified(1 - test_split, random_state=0))
 
 
-def fetch_UCILabelledCollection(dataset_name, data_home=None, verbose=False):
+def fetch_UCILabelledCollection(dataset_name, data_home=None, verbose=False) -> Dataset:
 
     assert dataset_name in UCI_DATASETS, \
         f'Name {dataset_name} does not match any known dataset from the UCI Machine Learning datasets repository. ' \
diff --git a/quapy/data/preprocessing.py b/quapy/data/preprocessing.py
index 77752f0..ee1627e 100644
--- a/quapy/data/preprocessing.py
+++ b/quapy/data/preprocessing.py
@@ -29,13 +29,13 @@ def text2tfidf(dataset:Dataset, min_df=3, sublinear_tf=True, inplace=False, **kw
     test_documents = vectorizer.transform(dataset.test.instances)
 
     if inplace:
-        dataset.training = LabelledCollection(training_documents, dataset.training.labels, dataset.n_classes)
-        dataset.test = LabelledCollection(test_documents, dataset.test.labels, dataset.n_classes)
+        dataset.training = LabelledCollection(training_documents, dataset.training.labels, dataset.classes_)
+        dataset.test = LabelledCollection(test_documents, dataset.test.labels, dataset.classes_)
         dataset.vocabulary = vectorizer.vocabulary_
         return dataset
     else:
-        training = LabelledCollection(training_documents, dataset.training.labels.copy(), dataset.n_classes)
-        test = LabelledCollection(test_documents, dataset.test.labels.copy(), dataset.n_classes)
+        training = LabelledCollection(training_documents, dataset.training.labels.copy(), dataset.classes_)
+        test = LabelledCollection(test_documents, dataset.test.labels.copy(), dataset.classes_)
         return Dataset(training, test, vectorizer.vocabulary_)
 
 
@@ -66,8 +66,8 @@ def reduce_columns(dataset: Dataset, min_df=5, inplace=False):
         dataset.test.instances = Xte
         return dataset
     else:
-        training = LabelledCollection(Xtr, dataset.training.labels.copy(), dataset.n_classes)
-        test = LabelledCollection(Xte, dataset.test.labels.copy(), dataset.n_classes)
+        training = LabelledCollection(Xtr, dataset.training.labels.copy(), dataset.classes_)
+        test = LabelledCollection(Xte, dataset.test.labels.copy(), dataset.classes_)
         return Dataset(training, test)
 
 
@@ -100,13 +100,13 @@ def index(dataset: Dataset, min_df=5, inplace=False, **kwargs):
     test_index = indexer.transform(dataset.test.instances)
 
     if inplace:
-        dataset.training = LabelledCollection(training_index, dataset.training.labels, dataset.n_classes)
-        dataset.test = LabelledCollection(test_index, dataset.test.labels, dataset.n_classes)
+        dataset.training = LabelledCollection(training_index, dataset.training.labels, dataset.classes_)
+        dataset.test = LabelledCollection(test_index, dataset.test.labels, dataset.classes_)
         dataset.vocabulary = indexer.vocabulary_
         return dataset
     else:
-        training = LabelledCollection(training_index, dataset.training.labels.copy(), dataset.n_classes)
-        test = LabelledCollection(test_index, dataset.test.labels.copy(), dataset.n_classes)
+        training = LabelledCollection(training_index, dataset.training.labels.copy(), dataset.classes_)
+        test = LabelledCollection(test_index, dataset.test.labels.copy(), dataset.classes_)
         return Dataset(training, test, indexer.vocabulary_)
 
 
diff --git a/quapy/data/reader.py b/quapy/data/reader.py
index 743b99e..5b4d115 100644
--- a/quapy/data/reader.py
+++ b/quapy/data/reader.py
@@ -3,7 +3,7 @@ from scipy.sparse import dok_matrix
 from tqdm import tqdm
 
 
-def from_text(path):
+def from_text(path, encoding='utf-8'):
     """
     Reas a labelled colletion of documents.
     File fomart <0 or 1>\t<document>\n
@@ -11,7 +11,7 @@ def from_text(path):
     :return: a list of sentences, and a list of labels
     """
     all_sentences, all_labels = [], []
-    for line in tqdm(open(path, 'rt').readlines(), f'loading {path}'):
+    for line in tqdm(open(path, 'rt', encoding=encoding).readlines(), f'loading {path}'):
         line = line.strip()
         if line:
             label, sentence = line.split('\t')
@@ -25,8 +25,8 @@ def from_text(path):
 
 def from_sparse(path):
     """
-    Reas a labelled colletion of real-valued instances expressed in sparse format
-    File fomart <-1 or 0 or 1>[\s col(int):val(float)]\n
+    Reads a labelled collection of real-valued instances expressed in sparse format
+    File format <-1 or 0 or 1>[\s col(int):val(float)]\n
     :param path: path to the labelled collection
     :return: a csr_matrix containing the instances (rows), and a ndarray containing the labels
     """
@@ -56,16 +56,16 @@ def from_sparse(path):
     return X, y
 
 
-def from_csv(path):
+def from_csv(path, encoding='utf-8'):
     """
-    Reas a csv file in which columns are separated by ','.
-    File fomart <label>,<feat1>,<feat2>,...,<featn>\n
+    Reads a csv file in which columns are separated by ','.
+    File format <label>,<feat1>,<feat2>,...,<featn>\n
     :param path: path to the csv file
     :return: a ndarray for the labels and a ndarray (float) for the covariates
     """
 
     X, y = [], []
-    for instance in tqdm(open(path, 'rt').readlines(), desc=f'reading {path}'):
+    for instance in tqdm(open(path, 'rt', encoding=encoding).readlines(), desc=f'reading {path}'):
         yi, *xi = instance.strip().split(',')
         X.append(list(map(float,xi)))
         y.append(yi)
diff --git a/quapy/functional.py b/quapy/functional.py
index 726b214..39a867b 100644
--- a/quapy/functional.py
+++ b/quapy/functional.py
@@ -36,12 +36,12 @@ def prevalence_linspace(n_prevalences=21, repeat=1, smooth_limits_epsilon=0.01):
     return p
 
 
-def prevalence_from_labels(labels, n_classes):
+def prevalence_from_labels(labels, classes_):
     if labels.ndim != 1:
         raise ValueError(f'param labels does not seem to be a ndarray of label predictions')
     unique, counts = np.unique(labels, return_counts=True)
     by_class = defaultdict(lambda:0, dict(zip(unique, counts)))
-    prevalences = np.asarray([by_class[ci] for ci in range(n_classes)], dtype=np.float)
+    prevalences = np.asarray([by_class[class_] for class_ in classes_], dtype=np.float)
     prevalences /= prevalences.sum()
     return prevalences
 
@@ -51,7 +51,7 @@ def prevalence_from_probabilities(posteriors, binarize: bool = False):
         raise ValueError(f'param posteriors does not seem to be a ndarray of posteior probabilities')
     if binarize:
         predictions = np.argmax(posteriors, axis=-1)
-        return prevalence_from_labels(predictions, n_classes=posteriors.shape[1])
+        return prevalence_from_labels(predictions, np.arange(posteriors.shape[1]))
     else:
         prevalences = posteriors.mean(axis=0)
         prevalences /= prevalences.sum()
diff --git a/quapy/method/__init__.py b/quapy/method/__init__.py
index 6ef83f1..b69d38f 100644
--- a/quapy/method/__init__.py
+++ b/quapy/method/__init__.py
@@ -3,21 +3,31 @@ from . import base
 from . import meta
 from . import non_aggregative
 
+EXPLICIT_LOSS_MINIMIZATION_METHODS = {
+    aggregative.ELM,
+    aggregative.SVMQ,
+    aggregative.SVMAE,
+    aggregative.SVMKLD,
+    aggregative.SVMRAE,
+    aggregative.SVMNKLD
+}
+
 AGGREGATIVE_METHODS = {
     aggregative.CC,
     aggregative.ACC,
     aggregative.PCC,
     aggregative.PACC,
-    aggregative.ELM,
     aggregative.EMQ,
     aggregative.HDy
-}
+} | EXPLICIT_LOSS_MINIMIZATION_METHODS
+
 
 NON_AGGREGATIVE_METHODS = {
     non_aggregative.MaximumLikelihoodPrevalenceEstimation
 }
 
 META_METHODS = {
+    meta.Ensemble,
     meta.QuaNet
 }
 
diff --git a/quapy/method/aggregative.py b/quapy/method/aggregative.py
index 34a10eb..ff94c21 100644
--- a/quapy/method/aggregative.py
+++ b/quapy/method/aggregative.py
@@ -1,6 +1,7 @@
 from abc import abstractmethod
 from copy import deepcopy
 from typing import Union
+
 import numpy as np
 from joblib import Parallel, delayed
 from sklearn.base import BaseEstimator
@@ -8,6 +9,7 @@ from sklearn.calibration import CalibratedClassifierCV
 from sklearn.metrics import confusion_matrix
 from sklearn.model_selection import StratifiedKFold
 from tqdm import tqdm
+
 import quapy as qp
 import quapy.functional as F
 from quapy.classification.svmperf import SVMperf
@@ -43,7 +45,7 @@ class AggregativeQuantifier(BaseQuantifier):
         return self.aggregate(classif_predictions)
 
     @abstractmethod
-    def aggregate(self, classif_predictions:np.ndarray): ...
+    def aggregate(self, classif_predictions: np.ndarray): ...
 
     def get_params(self, deep=True):
         return self.learner.get_params()
@@ -53,10 +55,10 @@ class AggregativeQuantifier(BaseQuantifier):
 
     @property
     def n_classes(self):
-        return len(self.classes)
+        return len(self.classes_)
 
     @property
-    def classes(self):
+    def classes_(self):
         return self.learner.classes_
 
     @property
@@ -84,7 +86,7 @@ class AggregativeProbabilisticQuantifier(AggregativeQuantifier):
 
     def set_params(self, **parameters):
         if isinstance(self.learner, CalibratedClassifierCV):
-            parameters = {'base_estimator__'+k:v for k,v in parameters.items()}
+            parameters = {'base_estimator__' + k: v for k, v in parameters.items()}
         self.learner.set_params(**parameters)
 
     @property
@@ -98,7 +100,7 @@ def training_helper(learner,
                     data: LabelledCollection,
                     fit_learner: bool = True,
                     ensure_probabilistic=False,
-                    val_split:Union[LabelledCollection, float]=None):
+                    val_split: Union[LabelledCollection, float] = None):
     """
     Training procedure common to all Aggregative Quantifiers.
     :param learner: the learner to be fit
@@ -122,13 +124,14 @@ def training_helper(learner,
             if isinstance(val_split, float):
                 if not (0 < val_split < 1):
                     raise ValueError(f'train/val split {val_split} out of range, must be in (0,1)')
-                train, unused = data.split_stratified(train_prop=1-val_split)
-            elif val_split.__class__.__name__ == LabelledCollection.__name__: #isinstance(val_split, LabelledCollection):
+                train, unused = data.split_stratified(train_prop=1 - val_split)
+            elif val_split.__class__.__name__ == LabelledCollection.__name__:  # isinstance(val_split, LabelledCollection):
                 train = data
                 unused = val_split
             else:
-                raise ValueError(f'param "val_split" ({type(val_split)}) not understood; use either a float indicating the split '
-                                 'proportion, or a LabelledCollection indicating the validation split')
+                raise ValueError(
+                    f'param "val_split" ({type(val_split)}) not understood; use either a float indicating the split '
+                    'proportion, or a LabelledCollection indicating the validation split')
         else:
             train, unused = data, None
 
@@ -153,7 +156,7 @@ class CC(AggregativeQuantifier):
     attributed each of the classes in order to compute class prevalence estimates.
     """
 
-    def __init__(self, learner:BaseEstimator):
+    def __init__(self, learner: BaseEstimator):
         self.learner = learner
 
     def fit(self, data: LabelledCollection, fit_learner=True):
@@ -167,16 +170,16 @@ class CC(AggregativeQuantifier):
         return self
 
     def aggregate(self, classif_predictions):
-        return F.prevalence_from_labels(classif_predictions, self.n_classes)
+        return F.prevalence_from_labels(classif_predictions, self.classes_)
 
 
 class ACC(AggregativeQuantifier):
 
-    def __init__(self, learner:BaseEstimator, val_split=0.4):
+    def __init__(self, learner: BaseEstimator, val_split=0.4):
         self.learner = learner
         self.val_split = val_split
 
-    def fit(self, data: LabelledCollection, fit_learner=True, val_split: Union[float, int, LabelledCollection]=None):
+    def fit(self, data: LabelledCollection, fit_learner=True, val_split: Union[float, int, LabelledCollection] = None):
         """
         Trains a ACC quantifier
         :param data: the training set
@@ -262,7 +265,7 @@ class PACC(AggregativeProbabilisticQuantifier):
         self.learner = learner
         self.val_split = val_split
 
-    def fit(self, data: LabelledCollection, fit_learner=True, val_split:Union[float, int, LabelledCollection]=None):
+    def fit(self, data: LabelledCollection, fit_learner=True, val_split: Union[float, int, LabelledCollection] = None):
         """
         Trains a PACC quantifier
         :param data: the training set
@@ -294,7 +297,8 @@ class PACC(AggregativeProbabilisticQuantifier):
             y_ = np.vstack(y_)
 
             # fit the learner on all data
-            self.learner, _ = training_helper(self.learner, data, fit_learner, ensure_probabilistic=True, val_split=None)
+            self.learner, _ = training_helper(self.learner, data, fit_learner, ensure_probabilistic=True,
+                                              val_split=None)
 
         else:
             self.learner, val_data = training_helper(
@@ -307,8 +311,8 @@ class PACC(AggregativeProbabilisticQuantifier):
         # estimate the matrix with entry (i,j) being the estimate of P(yi|yj), that is, the probability that a
         # document that belongs to yj ends up being classified as belonging to yi
         confusion = np.empty(shape=(data.n_classes, data.n_classes))
-        for yi in range(data.n_classes):
-            confusion[yi] = y_[y==yi].mean(axis=0)
+        for i,class_ in enumerate(data.classes_):
+            confusion[i] = y_[y == class_].mean(axis=0)
 
         self.Pte_cond_estim_ = confusion.T
 
@@ -338,7 +342,7 @@ class EMQ(AggregativeProbabilisticQuantifier):
 
     def fit(self, data: LabelledCollection, fit_learner=True):
         self.learner, _ = training_helper(self.learner, data, fit_learner, ensure_probabilistic=True)
-        self.train_prevalence = F.prevalence_from_labels(data.labels, self.n_classes)
+        self.train_prevalence = F.prevalence_from_labels(data.labels, self.classes_)
         return self
 
     def aggregate(self, classif_posteriors, epsilon=EPSILON):
@@ -366,7 +370,7 @@ class EMQ(AggregativeProbabilisticQuantifier):
             # M-step:
             qs = ps.mean(axis=0)
 
-            if qs_prev_ is not None and qp.error.mae(qs, qs_prev_) < epsilon and s>10:
+            if qs_prev_ is not None and qp.error.mae(qs, qs_prev_) < epsilon and s > 10:
                 converged = True
 
             qs_prev_ = qs
@@ -389,7 +393,7 @@ class HDy(AggregativeProbabilisticQuantifier, BinaryQuantifier):
         self.learner = learner
         self.val_split = val_split
 
-    def fit(self, data: LabelledCollection, fit_learner=True, val_split: Union[float, LabelledCollection]=None):
+    def fit(self, data: LabelledCollection, fit_learner=True, val_split: Union[float, LabelledCollection] = None):
         """
         Trains a HDy quantifier
         :param data: the training set
@@ -405,13 +409,15 @@ class HDy(AggregativeProbabilisticQuantifier, BinaryQuantifier):
         self._check_binary(data, self.__class__.__name__)
         self.learner, validation = training_helper(
             self.learner, data, fit_learner, ensure_probabilistic=True, val_split=val_split)
-        Px = self.posterior_probabilities(validation.instances)[:,1]  # takes only the P(y=+1|x)
-        self.Pxy1 = Px[validation.labels == 1]
-        self.Pxy0 = Px[validation.labels == 0]
+        Px = self.posterior_probabilities(validation.instances)[:, 1]  # takes only the P(y=+1|x)
+        self.Pxy1 = Px[validation.labels == self.learner.classes_[1]]
+        self.Pxy0 = Px[validation.labels == self.learner.classes_[0]]
         # pre-compute the histogram for positive and negative examples
-        self.bins = np.linspace(10, 110, 11, dtype=int)  #[10, 20, 30, ..., 100, 110]
-        self.Pxy1_density = {bins: np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)[0] for bins in self.bins}
-        self.Pxy0_density = {bins: np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)[0] for bins in self.bins}
+        self.bins = np.linspace(10, 110, 11, dtype=int)  # [10, 20, 30, ..., 100, 110]
+        self.Pxy1_density = {bins: np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)[0] for bins in
+                             self.bins}
+        self.Pxy0_density = {bins: np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)[0] for bins in
+                             self.bins}
         return self
 
     def aggregate(self, classif_posteriors):
@@ -419,12 +425,12 @@ class HDy(AggregativeProbabilisticQuantifier, BinaryQuantifier):
         # and the final estimated a priori probability was taken as the median of these 11 estimates."
         # (González-Castro, et al., 2013).
 
-        Px = classif_posteriors[:,1]  # takes only the P(y=+1|x)
+        Px = classif_posteriors[:, 1]  # takes only the P(y=+1|x)
 
         prev_estimations = []
-        #for bins in np.linspace(10, 110, 11, dtype=int):  #[10, 20, 30, ..., 100, 110]
-            #Pxy0_density, _ = np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)
-            #Pxy1_density, _ = np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)
+        # for bins in np.linspace(10, 110, 11, dtype=int):  #[10, 20, 30, ..., 100, 110]
+        # Pxy0_density, _ = np.histogram(self.Pxy0, bins=bins, range=(0, 1), density=True)
+        # Pxy1_density, _ = np.histogram(self.Pxy1, bins=bins, range=(0, 1), density=True)
         for bins in self.bins:
             Pxy0_density = self.Pxy0_density[bins]
             Pxy1_density = self.Pxy1_density[bins]
@@ -433,14 +439,14 @@ class HDy(AggregativeProbabilisticQuantifier, BinaryQuantifier):
 
             prev_selected, min_dist = None, None
             for prev in F.prevalence_linspace(n_prevalences=100, repeat=1, smooth_limits_epsilon=0.0):
-                Px_train = prev*Pxy1_density + (1 - prev)*Pxy0_density
+                Px_train = prev * Pxy1_density + (1 - prev) * Pxy0_density
                 hdy = F.HellingerDistance(Px_train, Px_test)
                 if prev_selected is None or hdy < min_dist:
                     prev_selected, min_dist = prev, hdy
             prev_estimations.append(prev_selected)
 
-        pos_class_prev = np.median(prev_estimations)
-        return np.asarray([1-pos_class_prev, pos_class_prev])
+        class1_prev = np.median(prev_estimations)
+        return np.asarray([1 - class1_prev, class1_prev])
 
 
 class ELM(AggregativeQuantifier, BinaryQuantifier):
@@ -457,8 +463,8 @@ class ELM(AggregativeQuantifier, BinaryQuantifier):
         self.learner.fit(data.instances, data.labels)
         return self
 
-    def aggregate(self, classif_predictions:np.ndarray):
-        return F.prevalence_from_labels(classif_predictions, self.learner.n_classes_)
+    def aggregate(self, classif_predictions: np.ndarray):
+        return F.prevalence_from_labels(classif_predictions, self.classes_)
 
     def classify(self, X, y=None):
         return self.learner.predict(X)
@@ -470,6 +476,7 @@ class SVMQ(ELM):
     Quantification-oriented learning based on reliable classifiers.
     Pattern Recognition, 48(2):591–604.
     """
+
     def __init__(self, svmperf_base=None, **kwargs):
         super(SVMQ, self).__init__(svmperf_base, loss='q', **kwargs)
 
@@ -480,6 +487,7 @@ class SVMKLD(ELM):
     Optimizing text quantifiers for multivariate loss functions.
     ACM Transactions on Knowledge Discovery and Data, 9(4):Article 27.
     """
+
     def __init__(self, svmperf_base=None, **kwargs):
         super(SVMKLD, self).__init__(svmperf_base, loss='kld', **kwargs)
 
@@ -490,6 +498,7 @@ class SVMNKLD(ELM):
     Optimizing text quantifiers for multivariate loss functions.
     ACM Transactions on Knowledge Discovery and Data, 9(4):Article 27.
     """
+
     def __init__(self, svmperf_base=None, **kwargs):
         super(SVMNKLD, self).__init__(svmperf_base, loss='nkld', **kwargs)
 
@@ -531,7 +540,7 @@ class OneVsAll(AggregativeQuantifier):
             f'{self.__class__.__name__} expect non-binary data'
         assert isinstance(self.binary_quantifier, BaseQuantifier), \
             f'{self.binary_quantifier} does not seem to be a Quantifier'
-        assert fit_learner==True, 'fit_learner must be True'
+        assert fit_learner == True, 'fit_learner must be True'
 
         self.dict_binary_quantifiers = {c: deepcopy(self.binary_quantifier) for c in data.classes_}
         self.__parallel(self._delayed_binary_fit, data)
@@ -559,11 +568,11 @@ class OneVsAll(AggregativeQuantifier):
 
     def aggregate(self, classif_predictions_bin):
         if self.probabilistic:
-            assert classif_predictions_bin.shape[1]==self.n_classes and classif_predictions_bin.shape[2]==2, \
+            assert classif_predictions_bin.shape[1] == self.n_classes and classif_predictions_bin.shape[2] == 2, \
                 'param classif_predictions_bin does not seem to be a valid matrix (ndarray) of posterior ' \
                 'probabilities (2 dimensions) for each document (row) and class (columns)'
         else:
-            assert set(np.unique(classif_predictions_bin)).issubset({0,1}), \
+            assert set(np.unique(classif_predictions_bin)).issubset({0, 1}), \
                 'param classif_predictions_bin does not seem to be a valid matrix (ndarray) of binary ' \
                 'predictions for each document (row) and class (columns)'
         prevalences = self.__parallel(self._delayed_binary_aggregate, classif_predictions_bin)
@@ -606,7 +615,7 @@ class OneVsAll(AggregativeQuantifier):
         return self.dict_binary_quantifiers[c].aggregate(classif_predictions[:, c])[1]
 
     def _delayed_binary_fit(self, c, data):
-        bindata = LabelledCollection(data.instances, data.labels == c, n_classes=2)
+        bindata = LabelledCollection(data.instances, data.labels == c, classes_=[False, True])
         self.dict_binary_quantifiers[c].fit(bindata)
 
     @property
@@ -616,9 +625,3 @@ class OneVsAll(AggregativeQuantifier):
     @property
     def probabilistic(self):
         return self.binary_quantifier.probabilistic
-
-
-
-
-
-
diff --git a/quapy/method/base.py b/quapy/method/base.py
index de53ad9..0c2729f 100644
--- a/quapy/method/base.py
+++ b/quapy/method/base.py
@@ -19,6 +19,10 @@ class BaseQuantifier(metaclass=ABCMeta):
     @abstractmethod
     def get_params(self, deep=True): ...
 
+    @property
+    @abstractmethod
+    def classes_(self): ...
+
     # these methods allows meta-learners to reimplement the decision based on their constituents, and not
     # based on class structure
     @property
diff --git a/quapy/method/meta.py b/quapy/method/meta.py
index d6c29d8..e74c969 100644
--- a/quapy/method/meta.py
+++ b/quapy/method/meta.py
@@ -186,6 +186,10 @@ class Ensemble(BaseQuantifier):
         order = np.argsort(dist)
         return _select_k(predictions, order, k=self.red_size)
 
+    @property
+    def classes_(self):
+        return self.base_quantifier.classes_
+
     @property
     def binary(self):
         return self.base_quantifier.binary
diff --git a/quapy/method/neural.py b/quapy/method/neural.py
index fc133f7..29a4127 100644
--- a/quapy/method/neural.py
+++ b/quapy/method/neural.py
@@ -58,6 +58,7 @@ class QuaNetTrainer(BaseQuantifier):
         self.device = torch.device(device)
 
         self.__check_params_colision(self.quanet_params, self.learner.get_params())
+        self._classes_ = None
 
     def fit(self, data: LabelledCollection, fit_learner=True):
         """
@@ -67,6 +68,7 @@ class QuaNetTrainer(BaseQuantifier):
         :param fit_learner: if true, trains the classifier on a split containing 40% of the data
         :return: self
         """
+        self._classes_ = data.classes_
         classifier_data, unused_data = data.split_stratified(0.4)
         train_data, valid_data = unused_data.split_stratified(0.66)  # 0.66 split of 60% makes 40% and 20%
 
@@ -256,6 +258,10 @@ class QuaNetTrainer(BaseQuantifier):
         import shutil
         shutil.rmtree(self.checkpointdir, ignore_errors=True)
 
+    @property
+    def classes_(self):
+        return self._classes_
+
 
 def mae_loss(output, target):
     return torch.mean(torch.abs(output - target))
diff --git a/quapy/method/non_aggregative.py b/quapy/method/non_aggregative.py
index 4defdeb..94b7c50 100644
--- a/quapy/method/non_aggregative.py
+++ b/quapy/method/non_aggregative.py
@@ -2,18 +2,22 @@ from quapy.data import LabelledCollection
 from .base import BaseQuantifier
 
 
-
 class MaximumLikelihoodPrevalenceEstimation(BaseQuantifier):
 
     def __init__(self, **kwargs):
-        pass
+        self._classes_ = None
 
     def fit(self, data: LabelledCollection, *args):
+        self._classes_ = data.classes_
         self.estimated_prevalence = data.prevalence()
 
     def quantify(self, documents, *args):
         return self.estimated_prevalence
 
+    @property
+    def classes_(self):
+        return self._classes_
+
     def get_params(self):
         pass
 
diff --git a/quapy/model_selection.py b/quapy/model_selection.py
index feeb14d..f78a576 100644
--- a/quapy/model_selection.py
+++ b/quapy/model_selection.py
@@ -4,7 +4,6 @@ from copy import deepcopy
 from typing import Union, Callable
 
 import quapy as qp
-import quapy.functional as F
 from quapy.data.base import LabelledCollection
 from quapy.evaluation import artificial_sampling_prediction
 from quapy.method.aggregative import BaseQuantifier
@@ -80,7 +79,7 @@ class GridSearchQ(BaseQuantifier):
             return training, validation
         elif isinstance(validation, float):
             assert 0. < validation < 1., 'validation proportion should be in (0,1)'
-            training, validation = training.split_stratified(train_prop=1-validation)
+            training, validation = training.split_stratified(train_prop=1 - validation)
             return training, validation
         else:
             raise ValueError(f'"validation" must either be a LabelledCollection or a float in (0,1) indicating the'
@@ -97,7 +96,7 @@ class GridSearchQ(BaseQuantifier):
             raise ValueError(f'unexpected error type; must either be a callable function or a str representing\n'
                              f'the name of an error function in {qp.error.QUANTIFICATION_ERROR_NAMES}')
 
-    def fit(self, training: LabelledCollection, val_split: Union[LabelledCollection, float]=None):
+    def fit(self, training: LabelledCollection, val_split: Union[LabelledCollection, float] = None):
         """
         :param training: the training set on which to optimize the hyperparameters
         :param val_split: either a LabelledCollection on which to test the performance of the different settings, or
@@ -118,6 +117,7 @@ class GridSearchQ(BaseQuantifier):
             def handler(signum, frame):
                 self.sout('timeout reached')
                 raise TimeoutError()
+
             signal.signal(signal.SIGALRM, handler)
 
         self.sout(f'starting optimization with n_jobs={n_jobs}')
@@ -175,6 +175,10 @@ class GridSearchQ(BaseQuantifier):
     def quantify(self, instances):
         return self.best_model_.quantify(instances)
 
+    @property
+    def classes_(self):
+        return self.best_model_.classes_
+
     def set_params(self, **parameters):
         self.param_grid = parameters
 
@@ -185,4 +189,3 @@ class GridSearchQ(BaseQuantifier):
         if hasattr(self, 'best_model_'):
             return self.best_model_
         raise ValueError('best_model called before fit')
-
diff --git a/quapy/tests/test_datasets.py b/quapy/tests/test_datasets.py
index 3f8f673..88209e8 100644
--- a/quapy/tests/test_datasets.py
+++ b/quapy/tests/test_datasets.py
@@ -6,13 +6,38 @@ from quapy.data.datasets import REVIEWS_SENTIMENT_DATASETS, TWITTER_SENTIMENT_DA
 
 @pytest.mark.parametrize('dataset_name', REVIEWS_SENTIMENT_DATASETS)
 def test_fetch_reviews(dataset_name):
-    fetch_reviews(dataset_name)
+    dataset = fetch_reviews(dataset_name)
+    print(f'Dataset {dataset_name}')
+    print('Training set stats')
+    dataset.training.stats()
+    print('Test set stats')
+    dataset.test.stats()
 
 
 @pytest.mark.parametrize('dataset_name', TWITTER_SENTIMENT_DATASETS_TEST + TWITTER_SENTIMENT_DATASETS_TRAIN)
 def test_fetch_twitter(dataset_name):
-    fetch_twitter(dataset_name)
+    try:
+        dataset = fetch_twitter(dataset_name)
+    except ValueError as ve:
+        if dataset_name == 'semeval' and ve.args[0].startswith(
+                'dataset "semeval" can only be used for model selection.'):
+            dataset = fetch_twitter(dataset_name, for_model_selection=True)
+    print(f'Dataset {dataset_name}')
+    print('Training set stats')
+    dataset.training.stats()
+    print('Test set stats')
 
-@pytest.mark.parametrize('dataset_name',  UCI_DATASETS)
+
+@pytest.mark.parametrize('dataset_name', UCI_DATASETS)
 def test_fetch_UCIDataset(dataset_name):
-    fetch_UCIDataset(dataset_name)
+    try:
+        dataset = fetch_UCIDataset(dataset_name)
+    except FileNotFoundError as fnfe:
+        if dataset_name == 'pageblocks.5' and fnfe.args[0].find(
+                'If this is the first time you attempt to load this dataset') > 0:
+            print('The pageblocks.5 dataset requires some hand processing to be usable, skipping this test.')
+            return
+    print(f'Dataset {dataset_name}')
+    print('Training set stats')
+    dataset.training.stats()
+    print('Test set stats')
diff --git a/quapy/tests/test_methods.py b/quapy/tests/test_methods.py
index 660c45e..186b7c0 100644
--- a/quapy/tests/test_methods.py
+++ b/quapy/tests/test_methods.py
@@ -1,24 +1,30 @@
 import numpy
 import pytest
 from sklearn.linear_model import LogisticRegression
-from sklearn.naive_bayes import MultinomialNB
 from sklearn.svm import LinearSVC
 
 import quapy as qp
+from quapy.data import Dataset, LabelledCollection
+from quapy.method import AGGREGATIVE_METHODS, NON_AGGREGATIVE_METHODS, EXPLICIT_LOSS_MINIMIZATION_METHODS
+from quapy.method.aggregative import ACC, PACC, HDy
+from quapy.method.meta import Ensemble
 
-datasets = [qp.datasets.fetch_twitter('semeval16')]
+datasets = [pytest.param(qp.datasets.fetch_twitter('hcr'), id='hcr'),
+            pytest.param(qp.datasets.fetch_UCIDataset('ionosphere'), id='ionosphere')]
 
-aggregative_methods = [qp.method.aggregative.CC, qp.method.aggregative.ACC, qp.method.aggregative.ELM]
-
-learners = [LogisticRegression, MultinomialNB, LinearSVC]
+learners = [LogisticRegression, LinearSVC]
 
 
 @pytest.mark.parametrize('dataset', datasets)
-@pytest.mark.parametrize('aggregative_method', aggregative_methods)
+@pytest.mark.parametrize('aggregative_method', AGGREGATIVE_METHODS.difference(EXPLICIT_LOSS_MINIMIZATION_METHODS))
 @pytest.mark.parametrize('learner', learners)
-def test_aggregative_methods(dataset, aggregative_method, learner):
+def test_aggregative_methods(dataset: Dataset, aggregative_method, learner):
     model = aggregative_method(learner())
 
+    if model.binary and not dataset.binary:
+        print(f'skipping the test of binary model {type(model)} on non-binary dataset {dataset}')
+        return
+
     model.fit(dataset.training)
 
     estim_prevalences = model.quantify(dataset.test.instances)
@@ -27,3 +33,147 @@ def test_aggregative_methods(dataset, aggregative_method, learner):
     error = qp.error.mae(true_prevalences, estim_prevalences)
 
     assert type(error) == numpy.float64
+
+
+@pytest.mark.parametrize('dataset', datasets)
+@pytest.mark.parametrize('elm_method', EXPLICIT_LOSS_MINIMIZATION_METHODS)
+def test_elm_methods(dataset: Dataset, elm_method):
+    try:
+        model = elm_method()
+    except AssertionError as ae:
+        if ae.args[0].find('does not seem to point to a valid path') > 0:
+            print('Missing SVMperf binary program, skipping test')
+            return
+
+    if model.binary and not dataset.binary:
+        print(f'skipping the test of binary model {model} on non-binary dataset {dataset}')
+        return
+
+    model.fit(dataset.training)
+
+    estim_prevalences = model.quantify(dataset.test.instances)
+
+    true_prevalences = dataset.test.prevalence()
+    error = qp.error.mae(true_prevalences, estim_prevalences)
+
+    assert type(error) == numpy.float64
+
+
+@pytest.mark.parametrize('dataset', datasets)
+@pytest.mark.parametrize('non_aggregative_method', NON_AGGREGATIVE_METHODS)
+def test_non_aggregative_methods(dataset: Dataset, non_aggregative_method):
+    model = non_aggregative_method()
+
+    if model.binary and not dataset.binary:
+        print(f'skipping the test of binary model {model} on non-binary dataset {dataset}')
+        return
+
+    model.fit(dataset.training)
+
+    estim_prevalences = model.quantify(dataset.test.instances)
+
+    true_prevalences = dataset.test.prevalence()
+    error = qp.error.mae(true_prevalences, estim_prevalences)
+
+    assert type(error) == numpy.float64
+
+
+@pytest.mark.parametrize('base_method', AGGREGATIVE_METHODS.difference(EXPLICIT_LOSS_MINIMIZATION_METHODS))
+@pytest.mark.parametrize('learner', learners)
+@pytest.mark.parametrize('dataset', datasets)
+@pytest.mark.parametrize('policy', Ensemble.VALID_POLICIES)
+def test_ensemble_method(base_method, learner, dataset: Dataset, policy):
+    qp.environ['SAMPLE_SIZE'] = len(dataset.training)
+    model = Ensemble(quantifier=base_method(learner()), size=5, policy=policy, n_jobs=-1)
+    if model.binary and not dataset.binary:
+        print(f'skipping the test of binary model {model} on non-binary dataset {dataset}')
+        return
+
+    model.fit(dataset.training)
+
+    estim_prevalences = model.quantify(dataset.test.instances)
+
+    true_prevalences = dataset.test.prevalence()
+    error = qp.error.mae(true_prevalences, estim_prevalences)
+
+    assert type(error) == numpy.float64
+
+
+def test_quanet_method():
+    dataset = qp.datasets.fetch_reviews('kindle', pickle=True)
+    dataset = Dataset(dataset.training.sampling(100, *dataset.training.prevalence()),
+                      dataset.test.sampling(100, *dataset.test.prevalence()))
+    qp.data.preprocessing.index(dataset, min_df=5, inplace=True)
+
+    from quapy.classification.neural import CNNnet
+    cnn = CNNnet(dataset.vocabulary_size, dataset.training.n_classes)
+
+    from quapy.classification.neural import NeuralClassifierTrainer
+    learner = NeuralClassifierTrainer(cnn, device='cuda')
+
+    from quapy.method.meta import QuaNet
+    model = QuaNet(learner, sample_size=len(dataset.training), device='cuda')
+
+    if model.binary and not dataset.binary:
+        print(f'skipping the test of binary model {model} on non-binary dataset {dataset}')
+        return
+
+    model.fit(dataset.training)
+
+    estim_prevalences = model.quantify(dataset.test.instances)
+
+    true_prevalences = dataset.test.prevalence()
+    error = qp.error.mae(true_prevalences, estim_prevalences)
+
+    assert type(error) == numpy.float64
+
+
+def models_to_test_for_str_label_names():
+    models = list()
+    learner = LogisticRegression
+    for method in AGGREGATIVE_METHODS.difference(EXPLICIT_LOSS_MINIMIZATION_METHODS):
+        models.append(method(learner()))
+    for method in NON_AGGREGATIVE_METHODS:
+        models.append(method())
+    return models
+
+
+@pytest.mark.parametrize('model', models_to_test_for_str_label_names())
+def test_str_label_names(model):
+    if type(model) in {ACC, PACC, HDy}:
+        print(
+            f'skipping the test of binary model {type(model)} because it currently does not support random seed control.')
+        return
+
+    dataset = qp.datasets.fetch_reviews('imdb', pickle=True)
+    dataset = Dataset(dataset.training.sampling(1000, *dataset.training.prevalence()),
+                      dataset.test.sampling(1000, *dataset.test.prevalence()))
+    qp.data.preprocessing.text2tfidf(dataset, min_df=5, inplace=True)
+
+    model.fit(dataset.training)
+
+    int_estim_prevalences = model.quantify(dataset.test.instances)
+    true_prevalences = dataset.test.prevalence()
+
+    error = qp.error.mae(true_prevalences, int_estim_prevalences)
+    assert type(error) == numpy.float64
+
+    dataset_str = Dataset(LabelledCollection(dataset.training.instances,
+                                             ['one' if label == 1 else 'zero' for label in dataset.training.labels]),
+                          LabelledCollection(dataset.test.instances,
+                                             ['one' if label == 1 else 'zero' for label in dataset.test.labels]))
+
+    model.fit(dataset_str.training)
+
+    str_estim_prevalences = model.quantify(dataset_str.test.instances)
+    true_prevalences = dataset_str.test.prevalence()
+
+    error = qp.error.mae(true_prevalences, str_estim_prevalences)
+    assert type(error) == numpy.float64
+
+    print(true_prevalences)
+    print(int_estim_prevalences)
+    print(str_estim_prevalences)
+
+    numpy.testing.assert_almost_equal(int_estim_prevalences[1],
+                                      str_estim_prevalences[list(model.classes_).index('one')])