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The q-value can be interpreted as the false discovery rate (FDR): the proportion of false positives among all positive results. Given a set of test statistics and their associated q-values, rejecting the null hypothesis for all tests whose q-value is less than or equal to some threshold ensures that the expected value of the false discovery rate is .
The p-values of the rejected null hypothesis (i.e. declared discoveries) are colored in red. Note that there are rejected p-values which are above the rejection line (in blue) since all null hypothesis of p-values which are ranked before the p-value of the last intersection are rejected. The approximations MFDR = 0.02625 and AFDR = 0.00730, here.
A hypothesis is rejected at level α if and only if its adjusted p-value is less than α. In the earlier example using equal weights, the adjusted p-values are 0.03, 0.06, 0.06, and 0.02. This is another way to see that using α = 0.05, only hypotheses one and four are rejected by this procedure.
The Bonferroni correction can also be applied as a p-value adjustment: Using that approach, instead of adjusting the alpha level, each p-value is multiplied by the number of tests (with adjusted p-values that exceed 1 then being reduced to 1), and the alpha level is left unchanged.
This expect-value is the product of the number of tests and the p-value. The q-value is the analog of the p-value with respect to the positive false discovery rate. [50] It is used in multiple hypothesis testing to maintain statistical power while minimizing the false positive rate. [51]
For example, for = 0.05 and m = 10, the Bonferroni-adjusted level is 0.005 and the Šidák-adjusted level is approximately 0.005116. One can also compute confidence intervals matching the test decision using the Šidák correction by computing each confidence interval at the (1 − α) 1/m % level.
Q factor (bicycles), the width between where a bicycle's pedals attach to the cranks; q-value (statistics), the minimum false discovery rate at which the test may be called significant; Q value (nuclear science), a difference of energies of parent and daughter nuclides; Q Score, in marketing, a way to measure the familiarity of an item
The procedures of Bonferroni and Holm control the FWER under any dependence structure of the p-values (or equivalently the individual test statistics).Essentially, this is achieved by accommodating a `worst-case' dependence structure (which is close to independence for most practical purposes).