Warning: This document is for an old version of Rasa NLU. The latest version is 0.15.1.

Evaluating and Improving Models

Improving your models from feedback

Once you have a version of your bot running, the Rasa NLU server will log every request made to the /parse endpoint to a file. By default these are saved in the folder logs.

{
  "user_input":{
    "entities":[]   ],
    "intent":{
      "confidence":0.32584617693743012,
      "name":"restaurant_search"
    },
    "text":"nice thai places",
    "intent_ranking":[ ... ]
  },
  ...
  "model":"default",
  "log_time":1504092543.036279
}

The things your users say are the best source of training data for refining your models. Of course your model won’t be perfect, so you will have to manually go through each of these predictions and correct any mistakes before adding them to your training data. In this case, the entity ‘thai’ was not picked up as a cuisine.

Evaluating Models

How is your model performing? Do you have enough data? Are your intents and entities well-designed?

Rasa NLU has an evaluate mode which helps you answer these questions. A standard technique in machine learning is to keep some data separate as a test set. If you’ve done this, you can see how well your model predicts the test cases using this command:

python -m rasa_nlu.evaluate \
    --data data/examples/rasa/demo-rasa.json \
    --model projects/default/model_20180323-145833

Where the --data argument points to your test data, and --model points to your trained model.

If you don’t have a separate test set, you can still estimate how well your model generalises using cross-validation. To do this, run the evaluation script with the --mode crossvalidation flag:

python -m rasa_nlu.evaluate \
    --data data/examples/rasa/demo-rasa.json \
    --config sample_configs/config_pretrained_embeddings_spacy.yml \
    --mode crossvalidation

You cannot specify a model in this mode because a new model will be trained on part of the data for every cross-validation fold.

Intent Classification

The evaluation script will produce a report, confusion matrix and confidence histogram for your model.

The report logs precision, recall and f1 measure for each intent and entity, as well as provide an overall average. You can save these reports as JSON files using the –report flag.

The confusion matrix shows you which intents are mistaken for others; any samples which have been incorrectly predicted are logged and saved to a file called errors.json for easier debugging.

The histogram that the script produces allows you to visualise the confidence distribution for all predictions, with the volume of correct and incorrect predictions being displayed by blue and red bars respectively. Improving the quality of your training data will move the blue histogram bars to the right and the red histogram bars to the left of the plot.

Note

A confusion matrix will only be created if you are evaluating a model on a test set. In cross-validation mode, the confusion matrix will not be generated.

Warning

If any of your entities are incorrectly annotated, your evaluation may fail. One common problem is that an entity cannot stop or start inside a token. For example, if you have an example for a name entity like [Brian](name)'s house, this is only valid if your tokenizer splits Brian's into multiple tokens. A whitespace tokenizer would not work in this case.

Entity Extraction

The CRFEntityExtractor is the only entity extractor which you train using your own data, and so is the only one which will be evaluated. If you use the spaCy or duckling pre-trained entity extractors, Rasa NLU will not include these in the evaluation.

Rasa NLU will report recall, precision, and f1 measure for each entity type that CRFEntityExtractor is trained to recognize.

Entity Scoring

To evaluate entity extraction we apply a simple tag-based approach. We don’t consider BILOU tags, but only the entity type tags on a per token basis. For location entity like “near Alexanderplatz” we expect the labels LOC LOC instead of the BILOU-based B-LOC L-LOC. Our approach is more lenient when it comes to evaluation, as it rewards partial extraction and does not punish the splitting of entities. For example, the given the aforementioned entity “near Alexanderplatz” and a system that extracts “Alexanderplatz”, this reward the extraction of “Alexanderplatz” and punish the missed out word “near”. The BILOU-based approach, however, would label this as a complete failure since it expects Alexanderplatz to be labeled as a last token in an entity (L-LOC) instead of a single token entity (U-LOC). Also note, a split extraction of “near” and “Alexanderplatz” would get full scores on our approach and zero on the BILOU-based one.

Here’s a comparison between the two scoring mechanisms for the phrase “near Alexanderplatz tonight”:

extracted	Simple tags (score)	BILOU tags (score)
[near Alexanderplatz](loc) [tonight](time)	loc loc time (3)	B-loc L-loc U-time (3)
[near](loc) [Alexanderplatz](loc) [tonight](time)	loc loc time (3)	U-loc U-loc U-time (1)
near [Alexanderplatz](loc) [tonight](time)	O loc time (2)	O U-loc U-time (1)
[near](loc) Alexanderplatz [tonight](time)	loc O time (2)	U-loc O U-time (1)
[near Alexanderplatz tonight](loc)	loc loc loc (2)	B-loc I-loc L-loc (1)

Evaluation Parameters

There are a number of parameters you can pass to the evaluation script. To see all options, run:

$ python -m rasa_nlu.evaluate --help

Which will produce the following output:

Calling `rasa_nlu.evaluate` is deprecated. Please use `rasa_nlu.test` instead.
usage: evaluate.py [-h] [--debug] [-v] -d DATA [--mode MODE] [-c CONFIG]
                   [-m MODEL] [-f FOLDS] [--report [REPORT]]
                   [--successes [SUCCESSES]] [--errors ERRORS]
                   [--histogram HISTOGRAM] [--confmat CONFMAT]

evaluate a Rasa NLU pipeline with cross validation or on external data

optional arguments:
  -h, --help            show this help message and exit
  --debug               Print lots of debugging statements. Sets logging level
                        to DEBUG
  -v, --verbose         Be verbose. Sets logging level to INFO
  -d DATA, --data DATA  file containing training/evaluation data
  --mode MODE           evaluation|crossvalidation (evaluate pretrained model
                        or train model by crossvalidation)
  -c CONFIG, --config CONFIG
                        model configuration file (crossvalidation only)
  -m MODEL, --model MODEL
                        path to model (evaluation only)
  -f FOLDS, --folds FOLDS
                        number of CV folds (crossvalidation only)
  --report [REPORT]     output path to save the intent/entitymetrics report
  --successes [SUCCESSES]
                        output path to save successful predictions
  --errors ERRORS       output path to save model errors
  --histogram HISTOGRAM
                        output path for the confidence histogram
  --confmat CONFMAT     output path for the confusion matrix plot

Have questions or feedback?

We have a very active support community on Rasa Community Forum that is happy to help you with your questions. If you have any feedback for us or a specific suggestion for improving the docs, feel free to share it by creating an issue on Rasa NLU GitHub repository.