More Powerful Tests from Confidence Interval p Values

A more powerful method to evaluate p-values in GENEHUNTER.

The determination of statistical significance in genetic linkage studies is complicated by many factors, such as missing individuals or uninformative markers, and the validity of theoretical results is often questionable. Although many simulation-based methods have been proposed to determine empirically the statistical significance, they are either not generally applicable to complex pedigree s...

On P values and confidence intervals (why can't we P with more confidence?)

How to obtain the P value from a confidence interval.

We have shown in a previous Statistics Note how we can calculate a confidence interval (CI) from a P value. Some published articles report confidence intervals, but do not give corresponding P values. Here we show how a confidence interval can be used to calculate a P value, should this be required. This might also be useful when the P value is given only imprecisely (eg, as P<0.05). Wherever t...

How to obtain the confidence interval from a P value.

Confidence intervals (CIs) are widely used in reporting statistical analyses of research data, and are usually considered to be more informative than P values from significance tests. 2 Some published articles, however, report estimated effects and P values, but do not give CIs (a practice BMJ now strongly discourages). Here we show how to obtain the confidence interval when only the observed e...

t-tests and p-values

We have discussed how to handle this test when σ is known. But how should we proceed if it is unknown? One option is the GLRT, discussed above. However, (a) we must estimate μ and (b) Wilk’s theorem only tells us that the test statistic corresponding to maximum likelihood estimates of σ and μ is asymptotically chi-squared. For small n, then, it can be difficult to set a threshold to achieve a d...