… I am trying to use the Hochberg correction on some data I have. The unadjusted ps look like this: Brids p=0.0001 Fish p=0.0009 Mammals = 0.1402 And after Hochberg like this using SAS PROC MULTEST: Brids p=0.0004 Fish p=0.0018 Mammals = 0.1402 The values in the correction just don’t seem right… For reference: http://www.statisticshowto.com/benjamini-hochberg-procedure/ How to Run the Benjamini–Hochberg procedure Put the individual p-values in ascending order. Assign ranks to the p-values. For example, the smallest has a rank of 1, the second smallest has a rank of 2. Calculate each individual p-value’s Benjamini-Hochberg critical value, using the formula (i/m)Q, where: i = the individual p-value’s rank, m = total number of tests, Q = the false discovery rate (a percentage, chosen by you). Compare your original p-values to the critical B-H from Step 3; find the largest p value that is smaller than the critical value. Step 1: So with our data they are already in order: Brids p=0.0001 Fish p=0.0009 Mammals = 0.1402 Step 2: Birds Rank 1 Fish Rank 2 Mammals Rank 3 Step 3: Birds: i=1 m=3 Q=0.05 (i/m)Q=(1/3)0.05=0.016 I am not sure what the Q value is in SAS and cannot find documentation. But, if you work back from the values provided by SAS 1/3x=0.016, then you get a Q of 0.0012. That seems like a strange value… also the Q would change…. For fish if 2/3Q=0.0018 then Q=0.0027 For mammals 3/3Q=0.1402, then Q=0.1402
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