# Multiple comparison correction (Bonferroni vs. Holm Boonferroni)

I have four questions:

1. If i have to run a test on 4 colors; red, blue, green, yellow. I ran the same test 4 times (one time on each color). (H1~H4) If i already have a predefined or existing reason to do each of these tests (not exploratory), do i have to correct for multiple comparison (no. of H/4)? What If it was exploratory?
2. If i have only 2 colored flowers; Black flowers and White flowers. I ran the same test 2 times (one time on each color). (H1~H2) But then i found something interesting to further investigate. E.g. the flower stem and leaves. If i were to correct for multiple comparisons for the stem and leaves. Do i divide the p-value by 2? or 4?
3. Which is better to use for the above Bonferroni or Holm-Bonferroni?
4. If i am correcting using the Holm-Bonferroni. Is it possible to report adjusted p values? If yes, how do you do that? e.g. in Bonferroni you multiply by the no. of tests run.
• I have one final Q. If i am correcting using the Holm-Bonferroni. Is it possible to report adjusted p values? If yes, how do you do that? e.g. in Bonferroni you divide by the no. of tests run. Jan 9 '18 at 5:07