Evaluation

[omriel1]

Original Task

Citing from the original course task:

Training a strong Hebrew Sentence Encoder from a pretrained Decoder While recent years
have brought many additions to the open-source set of pretrained LMs in high-resource languages such
as English, most of these tools are not directly useful for use on Hebrew Inputs. Recently, a new project
aiming to bridge this gap has introduced new tools and most importantly benchmarks for Herbrew LMs.
Concurrently, some new open-source strong models have been trained on Hebrew text, most recently, the
DictaLM 2.0. In this project, you will modify the DictaLM model to be a strong Encoder-model using
the LLM2Vec method. To evaluate the result, you will train linear classifier for a Hebrew sentiment
analysis task on top of embeddings from your trained model, and against some baselines. Such baselines
can be strong English and multilingual pretrained models, and existing pretrained Hebrew encoders (for
example, AlephBERT and AlephBERTGimmel).

See this github issue - huggingface/sentence-transformers#2547 (comment)
And read - https://huggingface.co/docs/setfit/conceptual_guides/setfit#classifier-training-phase

Data

Hebrew sentiment analysis dataset - https://huggingface.co/datasets/HebArabNlpProject/HebrewSentiment

As the benchmarks for hebrew sentiment used in Alephbert etc was proven as leaked

Classifier

We used the recommended approach of training a Logistic Regression classifier on top of the model embeddings, especially as recommended in:

1. Mistral blog (as our model is mistral-based) - https://github.com/mistralai/mistral-inference/blob/main/tutorials/classifier.ipynb
2. As demonstrated by the famous Jay Alamar - https://github.com/jalammar/jalammar.github.io/blob/master/notebooks/nlp/03_Sentence_Classification_with_BERT.ipynb
3. By huggingfaces' creators book - Natural Language Processing with Transformers, Revised Edition, chapter 2

[omriel1]

**Note: ** This results are using non-normalized embeddings! see next coment

First evaluation result, using the sklearn_classifier.py script: https://github.com/omriel1/llm2vec/blob/development/nlp_course/sklearn_classifier.py

See - https://github.com/omriel1/llm2vec/blob/development/nlp_course/experiments/v1/results.json

Logistic regression classifier

accuracy: 0.7723502304147466,
classification_report:

              precision    recall  f1-score   support

    Negative       0.70      0.75      0.72       433
     Neutral       0.82      0.80      0.81      1233
    Positive       0.73      0.72      0.73       503

    accuracy                           0.77      2170
   macro avg       0.56      0.57      0.56      2170
weighted avg       0.77      0.77      0.77      2170

Dummy most-frequent classifier

accuracy: 0.5682027649769585,
classification_report:

              precision    recall  f1-score   support

    Negative       0.00      0.00      0.00       433
     Neutral       0.57      1.00      0.72      1233
    Positive       0.00      0.00      0.00       503

    accuracy                           0.57      2170
   macro avg       0.14      0.25      0.18      2170
weighted avg       0.32      0.57      0.41      2170

Dummy uniform classifier

accuracy: 0.22995391705069124,
classification_report:

              precision    recall  f1-score   support

    Negative       0.19      0.25      0.22       433
     Neutral       0.53      0.23      0.32      1233
    Positive       0.20      0.21      0.20       503

    accuracy                           0.23      2170
   macro avg       0.23      0.17      0.19      2170
weighted avg       0.39      0.23      0.27      2170

[omriel1]

Nornmalize embeddings

Additional try with normalized embeddings (following https://github.com/mistralai/mistral-inference/blob/main/tutorials/classifier.ipynb):

Logistic regression classifier

20 iterations, C=1.0, random_state=0

accuracy: 0.8419354838709677
classification_report:

              precision    recall  f1-score   support

    Negative       0.82      0.81      0.82       433
     Neutral       0.85      0.89      0.87      1234
    Positive       0.83      0.75      0.79       503

    accuracy                           0.84      2170
   macro avg       0.83      0.82      0.83      2170
weighted avg       0.84      0.84      0.84      2170

Dummy most-frequent classifier

accuracy: 0.5686635944700461,
classification_report:

              precision    recall  f1-score   support

    Negative       0.00      0.00      0.00       433
     Neutral       0.57      1.00      0.73      1234
    Positive       0.00      0.00      0.00       503

    accuracy                           0.57      2170
   macro avg       0.19      0.33      0.24      2170
weighted avg       0.32      0.57      0.41      2170

Dummy uniform classifier

accuracy: 0.35069124423963133,
classification_report:

              precision    recall  f1-score   support

    Negative       0.21      0.36      0.26       433
     Neutral       0.59      0.35      0.44      1234
    Positive       0.26      0.36      0.30       503

    accuracy                           0.35      2170
   macro avg       0.35      0.35      0.33      2170
weighted avg       0.44      0.35      0.37      2170

[omriel1]

Additional results of training a classification head on top of the freezed model (the mntp-simcse model).
That is, the model itself is frezzed, and then we train a neural network classification head with the following architecture:

        self.linear_layer_stack = nn.Sequential(
            nn.Linear(self.embedding_dim, self.hidden_units, bias=False),
            nn.ReLU(),
            nn.Linear(self.hidden_units, self.num_labels, bias=False),
        )

Which of course gets into a softmax etc.

After 10 epochs of training, got this bad results:
accuracy: 0.48847926267281105
classification_report:

              precision    recall  f1-score   support

    Negative       0.30      0.91      0.45       433
     Neutral       0.79      0.52      0.63      1234
    Positive       0.72      0.04      0.08       503

    accuracy                           0.49      2170
   macro avg       0.60      0.49      0.39      2170
weighted avg       0.68      0.49      0.47      2170

[omriel1]

Comparison to other hebrew encoders:
Hebrew Encoders:

1. Alephbert
2. AlephbertGimmel

-> Note that both of this models are BERT based, hence output a vector embedding for each token, As usually done (see Jay Alamars' blog from above, and as learned in class), text classification in this settings is done using the embedding of the first token, the [CLS] token.

Multilingual:

1. intfloat/multilingual-e5-large
2. sentence-transformers/paraphrase-multilingual-mpnet-base-v2

Fine-tuned hebrew sentiment analysis models

1. DictaBERT-setiment

[omriel1]

Final results

1. I updated the results and found that for the LogisticRegression classifier, max_iter of 20 gets best results for our llm2vec.
2. Also, added two more embeddings models

LLM2Vec over DictaLM2.0 (Our trained model)

logistic_regression_classifier

accuracy: 0.840552995391705
classification_report:

              precision    recall  f1-score   support

    Negative       0.82      0.80      0.81       433
     Neutral       0.86      0.88      0.87      1234
    Positive       0.82      0.77      0.79       503

    accuracy                           0.84      2170
   macro avg       0.83      0.82      0.82      2170
weighted avg       0.84      0.84      0.84      2170

dummy_most_frequent_classifier

accuracy: 0.5686635944700461
classification_report:

              precision    recall  f1-score   support

    Negative       0.00      0.00      0.00       433
     Neutral       0.57      1.00      0.73      1234
    Positive       0.00      0.00      0.00       503

    accuracy                           0.57      2170
   macro avg       0.19      0.33      0.24      2170
weighted avg       0.32      0.57      0.41      2170

dummy_uniform_classifier

accuracy: 0.35069124423963133
classification_report:

              precision    recall  f1-score   support

    Negative       0.21      0.36      0.26       433
     Neutral       0.59      0.35      0.44      1234
    Positive       0.26      0.36      0.30       503

    accuracy                           0.35      2170
   macro avg       0.35      0.35      0.33      2170
weighted avg       0.44      0.35      0.37      2170

Neural Network classification head

Additional results of training a classification head on top of the freezed model (the mntp-simcse model).
That is, the model itself is freezed, and then we train a neural network classification head with the following architecture (we used hidden_units=8):

  self.linear_layer_stack = nn.Sequential(
      nn.Linear(self.embedding_dim, self.hidden_units, bias=False),
      nn.ReLU(),
      nn.Linear(self.hidden_units, self.num_labels, bias=False),
  )

Which of course gets into a softmax etc.

After 10 epochs of training, got this bad results:
accuracy: 0.48847926267281105
classification_report:

              precision    recall  f1-score   support

    Negative       0.30      0.91      0.45       433
     Neutral       0.79      0.52      0.63      1234
    Positive       0.72      0.04      0.08       503

    accuracy                           0.49      2170
   macro avg       0.60      0.49      0.39      2170
weighted avg       0.68      0.49      0.47      2170

Competitors

All results here are for same logistic regression classifiers with the same configurations as above

onlplab/alephbert-base

accuracy: 0.7889400921658987
classification_report:

              precision    recall  f1-score   support

    Negative       0.76      0.70      0.73       433
     Neutral       0.81      0.87      0.84      1234
    Positive       0.76      0.67      0.71       503

    accuracy                           0.79      2170
   macro avg       0.78      0.75      0.76      2170
weighted avg       0.79      0.79      0.79      2170

imvladikon/alephbertgimmel-base-512

accuracy: 0.7912442396313364
classification_report:

              precision    recall  f1-score   support

    Negative       0.80      0.70      0.74       433
     Neutral       0.80      0.87      0.83      1234
    Positive       0.76      0.67      0.71       503

    accuracy                           0.79      2170
   macro avg       0.79      0.75      0.76      2170
weighted avg       0.79      0.79      0.79      2170

intfloat/multilingual-e5-large

accuracy: 0.8064516129032258
classification_report:

              precision    recall  f1-score   support

    Negative       0.81      0.75      0.78       433
     Neutral       0.82      0.86      0.84      1234
    Positive       0.76      0.72      0.74       503

    accuracy                           0.81      2170
   macro avg       0.80      0.78      0.79      2170
weighted avg       0.81      0.81      0.81      2170

sentence-transformers/paraphrase-multilingual-mpnet-base-v2

accuracy: 0.7903225806451613
classification_report:

              precision    recall  f1-score   support

    Negative       0.76      0.73      0.75       433
     Neutral       0.80      0.86      0.83      1234
    Positive       0.79      0.67      0.72       503

    accuracy                           0.79      2170
   macro avg       0.78      0.75      0.77      2170
weighted avg       0.79      0.79      0.79      2170