Post hoc test r package
A false negative occurs when a test fails to produce a statistically significant result for an effect when it is really present. A test with a high false negative rate tends to miss effects. There is one line of thinking that says post hoc multiple comparisons tests of any kind should never be undertaken.Not all statistical packages support post-hoc analysis for Friedman's test, but user-contributed code exists that provides these facilities (for example in SPSS, and in R.). Also, there is a specialized package available in R containing numerous non-parametric methods for post-hoc analysis after Friedman.