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Joinpoint p-values

The Joinpoint Regression Program performs a series of hypothesis tests that test the null hypothesis of ka joinpoints against the alternative hypothesis of kb joinpoints, where ka and kb change for each hypothesis test. Each p-value corresponds to this type of test. The p-value is an estimate of the probability, under the assumption that there are only ka joinpoints, of observing data that look more like a joinpoint model with greater than ka joinpoints than the data that we have in fact observed.

As the permutation test is a randomization test, it depends on the random number generator. For greater consistency in the permutation test p-values obtained if one were to change the seed for each run, we suggest running the program for at least 4499 permutations. For this reason, the default number of permutations is now 4499 in the current version of the Joinpoint Regression Program. Choice of the number of permutations selected by the user is a trade off between computer time and consistency of the p-values obtained.

      

P-Value Precision and Display

The minimum precision for the P-Value on the Joinpoint Output’s Trends Tab has been set to 3 decimal places. Additionally, the P-Value will never be displayed as zero. For example, instead of “0.000” Joinpoint will display “<0.001”.