Six Sigma and Beyond: Statistics and Probability, Volume III

Here is what you should do when you want to design a study to explore an idea or question:

• You should carefully formulate your question and decide exactly what pieces of information are necessary to answer it.

• You must determine the population of interest and select a random sample of objects or people from the population.

• You must be sure that you do not unintentionally bias your sample by making it more likely that some members are included than others.

• You must collect your information in an objective fashion. The procedure for gathering the information must be objective and standardized. Questions must be unambiguous.

• If several different conditions are to be compared, you must ensure that the subjects are randomly allocated to the groups.

• You must prevent the subjects and investigators from allowing their personal prejudices to influence the outcome of the investigation.