dataeval.metrics.bias.parity

dataeval.metrics.bias.parity(metadata)

Calculate chi-square statistics to assess the linear relationship between multiple factors and class labels.

This function computes the chi-square statistic for each metadata factor to determine if there is a significant relationship between the factor values and class labels. The chi-square statistic is only valid for linear relationships. If non-linear relationships exist, use balance.

Parameters:
metadata : Metadata

Preprocessed metadata

Returns:

Arrays of length (num_factors) whose (i)th element corresponds to the chi-square score and p-value for the relationship between factor i and the class labels in the dataset.

Return type:

ParityOutput[NDArray[np.float64]]

Raises:

Warning – If any cell in the contingency matrix has a value between 0 and 5, a warning is issued because this can lead to inaccurate chi-square calculations. It is recommended to ensure that each label co-occurs with factor values either 0 times or at least 5 times.

Note

  • A high score with a low p-value suggests that a metadata factor is strongly correlated with a class label.

  • The function creates a contingency matrix for each factor, where each entry represents the frequency of a specific factor value co-occurring with a particular class label.

  • Rows containing only zeros in the contingency matrix are removed before performing the chi-square test to prevent errors in the calculation.

See also

balance

Examples

Randomly creating some “continuous” and categorical variables using np.random.default_rng

>>> metadata = generate_random_metadata(
...     labels=["doctor", "artist", "teacher"],
...     factors={
...         "age": [25, 30, 35, 45],
...         "income": [50000, 65000, 80000],
...         "gender": ["M", "F"]},
...     length=100,
...     random_seed=175)

>>> parity(metadata)
ParityOutput(score=array([7.357, 5.467, 0.515]), p_value=array([0.289, 0.243, 0.773]), factor_names=['age', 'income', 'gender'], insufficient_data={'age': {35: {'artist': 4}, 45: {'artist': 4, 'teacher': 3}}, 'income': {50000: {'artist': 3}}})