Reading a research article part III: the data collection instrument.

Parts I through III of this series of articles gave an introduction to some of the issues requiring attention when performing clinical studies and summarizing the results statistically as well as clinically. Statistical methods have been described for the identification of statistically significant differences and associations between an experimental group and a control group or over the course of time after an intervention. The next article will address the methods used for the determination of the strength or magnitude of these identified statistically significant differences.