For many of us work in medical informatics as a profession or advocation, the question of the computer-based patient record is not whether or not it is of benefit but when and how it will be implemented. A growing literature assesses CDSS and a means of evaluating this literature is timely. A number of errors may arise in any of these areas.
Randomization affects a study's validity.
A common mistake is a unit of analysis error, when unit of study is not a number of patients but a smaller number of physicians or groups of physicians. Cluster randomization can eliminate this kind of bias. Contamination of the control group by the CDSS may reduce validity. An example of contamination would be cross-coverage when the control group and the intervention group of physicians may cover each others patients. If the results of the control group are tabulated manually but the results of the intervention group are collected electronically, reporting bias may be relevant.