¶ … B; no interaction). B. A x B. interaction; C. Main effect B. only.
First, counterbalancing the design of the experiment would control for practice effects. In this case the carry-over effect is in one direction. Counterbalancing the conditions leads to the subjects being exposed to different levels of the IV in different orders. Working on lower levels of color variability prepares one to work more efficiently on higher levels of color variability. Counterbalancing the conditions balances out the carry over effects because some subjects start at lower levels of color variability and others at higher levels. As a result of counterbalancing the practice effects are canceled out.
A major disadvantage of repeated measures designs are carry-over effects. The researcher could also control for practice effects by incorporating a between subjects design and simply comparing the performance of the matched pairs on at different levels of color variability and not having each subject work through all the levels. However, this would result in the need for significantly more participants (a much higher N) than a repeated measures design.
3. A researcher is interested in how people judge people perceived as similar to them and how they judge individuals perceived as different from them...
The researcher sets up a minimal groups paradigm where participants are told that they are either over estimators or under estimators based on estimations of dots presented on an overhead screen (in reality this is deception the researcher randomly assigns subjects to the over estimator or under estimator group). Once the person is told of which group they are in their asked to evaluate both their in group and the out group on a number of different measures. The researcher performs this study at a suburban private college using the psychology subject pool. The students at the college are primarily male, Caucasian, and upper-middle-class. Thus his sample is biased in terms of these parameters because of the limitations of gender, ethnicity, and social economic status.
One way to control for this sampling bias would be to attempt to develop parameters for a stratified sample of participants where there is more equity on these demographic variables. In this case a stratified sample would help to increase the ability to generalize from the findings compared to simply not trying to control the demographic characteristics of participants. This may also require the researcher to go outside of the current research setting to a different venue in order to fulfill the…
