Do not zero out one-tailed z-statistics for p-values > 0.5

[JulioAPeraza]

Closes #511.

Changes proposed in this pull request:

• Do not zero out one-tailed z-statistics for p-values > 0.5. Note: p-value = 0.5 will still be set to 0, so logp and z-statistic maps will not completely match in that case.

[codecov[bot]]

Codecov Report

Base: 88.64% // Head: 88.66% // Increases project coverage by +0.02% :tada:

Coverage data is based on head (e6cb5e2) compared to base (2de404d). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #693      +/-   ##
==========================================
+ Coverage   88.64%   88.66%   +0.02%     
==========================================
  Files          38       38              
  Lines        4324     4323       -1     
==========================================
  Hits         3833     3833              
+ Misses        491      490       -1     

Impacted Files	Coverage Δ
nimare/decode/continuous.py	94.79% <ø> (ø)
nimare/io.py	95.14% <ø> (ø)
nimare/meta/cbma/ale.py	96.61% <ø> (ø)
nimare/meta/cbma/mkda.py	98.75% <ø> (ø)
nimare/meta/kernel.py	95.78% <ø> (ø)
nimare/meta/utils.py	95.73% <ø> (ø)
nimare/extract/utils.py	38.58% <100.00%> (ø)
nimare/transforms.py	75.63% <100.00%> (+0.27%)	:arrow_up:

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[JulioAPeraza]

@tsalo if we don't zero out one-tailed z-statistics for p-values > 0.5, should we: (1) leave the negative value, (2) apply the abs() function since the values returned by this function should be unsigned z-statistics, or (3) replace the negative values with a small number 1.0e-300?

[tsalo]

I'm not sure... maybe someone else who has a better handle on stats can answer that?

[tsalo]

@yifan0330 seemed to have a good handle on z-to-p conversion (and probably p-to-z conversion), given #748 and #749. @yifan0330 would you be willing to take a look at this?

[yifan0330]

@yifan0330 seemed to have a good handle on z-to-p conversion (and probably p-to-z conversion), given #748 and #749. @yifan0330 would you be willing to take a look at this?

@JulioAPeraza @tsalo I saw you replace negative z value with values estimated by cdf, I am wondering if it's the same as taking absolute value of z (since z and zval_cdf have same value but opposite sign)? Also, I left two comments on testing case (I think z=-1.959964 corresponds to p=0.975 in one tail test).

[JulioAPeraza]

Thanks so much, @yifan0330! I've incorporated your suggestions. @tsalo Do you think this is ready to merge?

[yifan0330]

@JulioAPeraza if @yifan0330 is happy with the changes then absolutely, I think it's good to merge.

Yeah I am happy with Julio's changes :)

[JulioAPeraza]

Thanks! Merging now.