Bug: McNemar Continuity-correction Arg Is Ignored By `print_mcnemar`.

Apr 25, 2025 by ADMIN 70 views

Bug: McNemar Continuity-Correction Argument is Ignored by print_mcnemar

In the realm of statistical analysis, the McNemar test is a non-parametric statistical test used to determine whether there is a significant difference between the number of times a particular outcome occurs in two related samples. The test is commonly used in medical research, quality control, and other fields where paired data is collected. However, a recent issue has been discovered in the print_mcnemar function, which is used to print the results of the McNemar test. In this article, we will delve into the details of the bug and explore the simple fix that has been proposed.

The bug in question is related to the print_mcnemar function, which is used to print the results of the McNemar test. Specifically, the issue lies in the way the continuity_correction argument is handled. The continuity_correction argument is used to determine whether to apply a continuity correction to the test statistic. However, in the print_mcnemar function, this argument is always set to True, regardless of the value provided by the user.

Code Snippet

The relevant code snippet from the mcnemar.py file is shown below:

def print_mcnemar(args):
    ...
    result = _mcnemar(args, continuity_correction=True)
    ...

As can be seen from the code snippet, the continuity_correction argument is always set to True when calling the _mcnemar method. This means that the value of the continuity_correction argument provided by the user is ignored, and the test is always performed with continuity correction.

Consequences of the Bug

The consequences of this bug are significant. When the continuity_correction argument is set to False, the test should not apply continuity correction. However, due to the bug, the test is always performed with continuity correction, regardless of the value of the continuity_correction argument. This can lead to incorrect results and potentially misleading conclusions.

Simple Fix

Fortunately, the fix for this bug is simple. The print_mcnemar function should use the value of the args.continuity_correction argument instead of always providing True to the _mcnemar method. This can be achieved by modifying the code snippet as follows:

def print_mcnemar(args):
    ...
    result = _mcnemar(args, continuity_correction=args.continuity_correction)
    ...

By making this simple change, the value of the continuity_correction argument provided by the user is respected, and the test is performed with or without continuity correction, depending on the user's preference.

In conclusion, the bug in the print_mcnemar function is a significant issue that can lead to incorrect results and potentially misleading conclusions. However, the fix is simple and can be achieved by modifying the code snippet to use the value of the args.continuity_correction argument. We hope that this article has provided a clear understanding of the bug and the simple fix that has been proposed.

As the for this bug is simple and has been proposed, it is expected that the issue will be resolved shortly. However, it is essential to continue testing and validating the results to ensure that the fix has not introduced any new issues. Additionally, it is recommended to review the code and ensure that similar bugs are not present in other parts of the codebase.

Based on the analysis of the bug and the proposed fix, we recommend the following:

Review the code and ensure that similar bugs are not present in other parts of the codebase.
Continue testing and validating the results to ensure that the fix has not introduced any new issues.
Consider adding additional checks and validation to ensure that the continuity_correction argument is respected.

[1] GitHub repository for Chart Review: https://github.com/smart-on-fhir/chart-review
[2] McNemar test: https://en.wikipedia.org/wiki/McNemar's_test

We would like to thank the developers of the Chart Review project for their hard work and dedication to creating a high-quality tool for statistical analysis. We also appreciate the prompt response and proposed fix for the bug.
Bug: McNemar Continuity-Correction Argument is Ignored by print_mcnemar - Q&A

In our previous article, we discussed the bug in the print_mcnemar function, which is used to print the results of the McNemar test. The bug is related to the continuity_correction argument, which is always set to True regardless of the value provided by the user. In this article, we will answer some frequently asked questions (FAQs) related to the bug and its fix.

A: The McNemar test is a non-parametric statistical test used to determine whether there is a significant difference between the number of times a particular outcome occurs in two related samples.

A: The continuity_correction argument is used to determine whether to apply a continuity correction to the test statistic. When True, the test applies a continuity correction, and when False, it does not.

A: The continuity_correction argument is ignored in the print_mcnemar function because the code always sets it to True when calling the _mcnemar method.

A: Ignoring the continuity_correction argument can lead to incorrect results and potentially misleading conclusions. When the user sets continuity_correction to False, the test should not apply continuity correction. However, due to the bug, the test is always performed with continuity correction.

A: The bug can be fixed by modifying the print_mcnemar function to use the value of the args.continuity_correction argument instead of always providing True to the _mcnemar method.

A: The proposed fix is to modify the print_mcnemar function as follows:

def print_mcnemar(args):
    ...
    result = _mcnemar(args, continuity_correction=args.continuity_correction)
    ...

A: It is essential to continue testing and validating the results to ensure that the fix has not introduced any new issues.

A: To prevent similar bugs in the future, it is recommended to review the code and ensure that similar bugs are not present in other parts of the codebase. Additionally, consider adding additional checks and validation to ensure that user-provided arguments are respected.

A: You can find more information about the bug and its fix in the GitHub repository for Chart Review: https://github.com/smart-on-fhir/chart-review.

In conclusion, the bug in the _mcnemar function is a significant issue that can lead to incorrect results and potentially misleading conclusions. However, the fix is simple and can be achieved by modifying the code snippet to use the value of the args.continuity_correction argument. We hope that this Q&A article has provided a clear understanding of the bug and its fix.