In the GreyListChIP manual, for the calcThreshold function, the p parameter is defined as 'The p-value threshold for marking bins as “grey”

The default value of that value is 0.99.

The general definition of p-value is the the probability of obtaining the test results (or test results that are at least as extreme as the ones obtained) under the assumption of the null hypothesis.

What is the null hypothesis for the statistical test that calcThreshold performs?