Using more than two groups in an experiment also allows researchers to determine whether each treatment is more or less effective than no treatment (the control group).To illustrate this, imagine that we are interested in the effects of aerobic exerc ..Read More

This design is similar to the pretest-posttest except that there are more than two measurements. Ideally, there are an equal number of measurement periods before and after treatment, and the period between measurements is constant. These designs can ..Read More

When conducting correlational studies, research determine whether two variables (for example, height and weight or smoking and cancer) are related to each other. Such studies assess whether the variables are “corre-lated” in some way: Do ..Read More

Obviously, a measure should be more reliable and valid. It is possible, however, to have a test or measure that meets one of these criteria and not the other. Think for a moment about how this might would occur. Can a test be reliable without being v ..Read More