OptinMon 25 - Effect Size Statistics

5 Ways to Increase Power in a Study

June 12th, 2009 by

To increase power:

  1. Increase alpha
  2. Conduct a one-tailed test
  3. Increase the effect size
  4. Decrease random error
  5. Increase sample size

Sound so simple, right?  The reality is that although these 5 ways all work (more…)


5 Steps for Calculating Sample Size

November 12th, 2008 by

Nearly all granting agencies require an estimate of an adequate sample size to detect the effects hypothesized in the study. But all studies are well served by estimates of sample size, as it can save a great deal on resources.

stage 1

Why? Undersized studies can’t find real results, and oversized studies find even insubstantial ones. Both undersized and oversized studies waste time, energy, and money; the former by using resources without finding results, and the latter by using more resources than necessary. Both expose an unnecessary number of participants to experimental risks.

The trick is (more…)