Interesting website: Bayesian Unconditional Power Analysis (John S. Uebersax). URL: ourworld.compuserve.com/homepages/jsuebersax/bpower.htm.

When you perform a traditional power calculation, you need to specify the size of the difference that you want to detect. Sometimes this represents the minimum difference that is clinically relevant and sometimes it is a difference that is observed in a previous research study. If the latter is chosen, you need to account for sampling error in the previously observed difference. Otherwise the estimated power is biased, often biased downward.

The description of this website was written on 2007-07-24, and was last modified on 2008-06-21. This website was last verified on 2007-07-24. Category: Interesting websites, Category: Sample size justification.