One of the most interesting introductions to the idea of
statistical power is given in the 'OJ' Page which was created by
Rob Becker to illustrate how the decision a jury has to reach
(guilty vs. not guilt) is similar to the decision a researcher
makes when assessing a relationship. The OJ Page uses the
infamous OJ Simpson murder trial to introduce the idea of
statistical power and illustrate how manipulating various
factors (e.g., the amount of evidence, the "effect size", and
the level of risk) affects the validity of the verdict. There
are four interrelated components that influence the conclusions
you might reach from a statistical test in a research project.
The logic of statistical inference with respect to these
components is often difficult to understand and explain. This
paper attempts to clarify the four components and describe their
interrelationships. The four components are: - sample size, or
the number of units (e.g., people) accessible to the study -
effect size, or the salience of the treatmen