Elo estimates of single patches (SPRT runs) typically come with large error bars. Take this into account when adding Elo estimates. Furthermore, Elo estimates of passing patches are biased. The SPRT Elo estimates are only unbiased if one takes all patches into account, both passed and non-passed ones. As a result, the Elo gain measured by a regression test will typically be less than the sum of the estimated Elo gains of the individual patches since the previous regression test.
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