feat(stats): implement additional statistical tests #17

[Sumithraju]

Description

What is the purpose of this pull request?

This pull request:

• adds @stdlib/stats/spearman-test which computes a Spearman rank correlation test between paired samples

The Spearman rank correlation coefficient is a non-parametric measure of rank correlation that assesses how well the relationship between two variables can be described using a monotonic function.

The implementation closely follows the existing pcorrtest package patterns and supports:

• Two-sided, less, and greater alternative hypotheses
• Custom significance level (alpha)
• Testing against a non-zero null correlation (rho)
• Confidence intervals via Fisher's z transform
• Pretty-printed output via .print() method
• Tied rank handling via average rank assignment

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [Idea]: implement additional statistical tests google-summer-of-code#17

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

• Implementation mirrors the structure and conventions of @stdlib/stats/pcorrtest
• Uses t-test when rho = 0 and Fisher's z transform when rho != 0, consistent with R's cor.test(method = "spearman")
• R fixture runner script included at test/fixtures/r/runner.R for cross-validation

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

• Yes
• No

If you answered "yes" above, how did you use AI assistance?

• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
• Documentation (including examples)
• Research and understanding

Disclosure

This PR was scaffolded with AI assistance . All code was reviewed and validated manually by the author.

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/spearman-test	$\color{red}623/649$ $\color{green}+95.99%$	$\color{red}70/77$ $\color{green}+90.91%$	$\color{green}6/6$ $\color{green}+100.00%$	$\color{red}623/649$ $\color{green}+95.99%$

The above coverage report was generated for the changes in this PR.

[Sumithraju]

infrastructure err not in my code how do i fix it