Dr. Schwab is using a behavioral assessment. He is identifying and measuring target behaviors and their controlling variables in an individual's natural environment.

A placebo is an inert substance that participants believe is the actual treatment or drug. Placebos have been found to be, in some cases, effective in treatment, and they have also been used to test the efficacy of drugs.

A between-subjects design involves using different participants in the control and experimental groups. There is no overlap in the conditions. Within-subjects design uses the same participants in multiple treatments.

Surveys rely solely on answers that were given to the participants therefore in certain categories (like in sex studies) subjects may give false answers in order to maintain social order. Although it is difficult to get a representative sample of the population, it is possible to get a sample that is large enough and random enough to represent the whole population. Survey questions can readily be made to be objective. Surveys are relatively easy to perform once participation is addressed.

Since case studies only involve one situation, they may lead to the over-generalization of a condition that is rare and/or specific to a certain situation. 

This example is a double blind study. In a double blind study, both the subjects and researchers do not know which individuals are given the placebo and which are given the actual treatment. This type of study can control for the placebo effect and researcher bias. 

The population would be all the college students that have taken standardized tests in the country the psychologist resides in because a population is all the possible individuals in a group that a sample can be pulled from. It is most likely not possible that the researcher would be able to include the entire population in his study due to the large size.

When researchers assign study participants to different groups based on chance, such as by using a random number generator or flipping a coin as her, this is an example of random assignment. A method that is not random assignment would be something like assigning all men to one group and all women to another. Random assignment is sometimes confused with random selection, which means choosing study participants at random from the population being studied.

Experimental research designs allow researchers to carefully control each variable measured. This level of control allows researchers to establish causal connections between variables and allows other researchers to know exactly how to repeat the study on their own; however, this control also confines the study to variables that can be observed in a laboratory setting. Unlike descriptive studies, in which participants might not always know they are being observed, experiments force researchers to brief their participants on how they will participate, and allow participants to decline or leave.

We know that Dr. Andrews used a longitudinal design because the question tells us that he tracks the same group of children’s progress at regular intervals. This is the definition of a longitudinal study design: the same group of individuals is observed, measured, tested, etc. on the same dependent variable at regular time intervals. This allows the researcher to see how a certain measured trait changes in individuals over time; however, longitudinal studies take a long time to carry out and are quite expensive. As a result, many researchers use an alternative cross-sectional design, which uses two or more different groups of subjects that are relatively similar except in age and measures them just once.