In Jill's study, she is interested in testing the efficacy of a preventive treatment. Thus her response variable is whether or not the mouse gets the disease of interest which is qualitative. This variable will be coded as a 1 if the disease of interest occurs and a 0 if the disease does not occur. This type of variable is called binary or dichotomous. If Jill were interested in a qualitative variable that is not binary then we may recommend that she dichotomize her variable. If she feels that dichotomizing her variable will force a significant loss of information then perhaps she should consider her variable as a quantitative response. For the rest of this discussion we will assume that the response variable of interest is response / nonresponse.

Now that we have determined the response variable being measured, we need to determine the type of trial design you want to use. Which of the following designs are you planning to use? -- ErinEsp - 31 Jan 2010