Adjust CIs when adjusting pvalues

[lukesonnet]

Features

Right now we don't update our CIs when we apply multiple comparisons corrections.

There isn't a great way to do this for all tests because:

1. Existing methods (Benjamini & Yeukateli 2005) only apply to selected parameters
2. Ad-hoc methods (finding a std-dev that matches to the adjusted "p"-value) don't handle the common case where adjusted "p"-values are 1.

See the thread on this here: https://linen.growthbook.io/t/13221597/hi-u01tcpdb58c-u01t6hchd0a-and-u03gc3g9e8m-we-re-using-the-e

Nonetheless, having CIs out of sync with the p-values is disorienting and a bad user experience.

So we implemented a variant of the ad-hoc method (item 2 above) to adjust CIs when an org implements multiple comparisons corrections:

1. For all adjusted p-values, compute the implied stddev that would have yielded that p-value (note we use a z test in the app because only the stats engine has access to the true DoF we used for the t test; this should not matter for this method but could be improved). If the p-value is > 0.999999, we set the CI to be infinite.
2. Using that implied stddev, compute new CIs
3. If the new CIs are wider than the old CIs; overwrite the old CIs in the front-end.

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