Mathematics three assignments | him325 | DeVry University - Downers Grove, IL
- Independent Samples t-Test: The Independent Samples t-Test procedure compares means for two groups of cases. Ideally, for this test, the subjects should be randomly assigned to two groups, so that any difference in response is due to the treatment (or lack of treatment) and not to other factors. Example. Patients with high blood pressure are randomly assigned to a placebo group and a treatment group. The placebo subjects receive an inactive pill, and the treatment subjects receive a new drug that is expected to lower blood pressure. After the subjects are treated for two months, the 2-Sample t-Test is used to compare the average blood pressures for the placebo group and the treatment group. Each patient is measured once and belongs to one group.
Note: Patients with high blood pressure are not normally left untreated – this is an ethical question that arises all the time in healthcare studies. Could one ethically conduct such a study? Would such a study receive approval from the administration and medical boards? What legal issues would need to be addressed? The Independent Samples t-Test is appropriate whenever two means drawn from independent samples are to be compared. The variable used to form the groups may already exist; however, a cut point on a continuous variable can be provided to dynamically create the groups during the analysis. As with all t-Tests, the Independent Samples t-Test assumes that each sample mean comes from a population that is reasonably normally distributed, especially with respect to skewness. Test variables with extreme or outlying values should be carefully checked; boxplots can be used for this.