Q1)a) Categorize according to most descriptive or definitive category of research strategies (i.e., experiments, naturalistic observations, surveys, case-control studies, cohort studies, quasi-experiments, longitudinal vs. cross-sectional studies, matched design, retrospective vs. prospective studies, time-series, single-subject studies).

b) Recognize features of study that prompted your classification.

c) Recognize the IV, DV, and other variables, if suitable.

d) Recognize and describe potential threats (up to 3) to internal validity.

e) Recognize and explain potential threats (up to 3) to external validity.

f) Recognize strategies that were utilized to control for nuisance variables and minimize threats to valid inference making.

g) What additional strategies (up to 3) you would propose that may increase validity of the findings

200 sixth-graders took a test which measured arithmetic achievement. These students were matched on basis of their achievement scores. One member of each pair was arbitrarily assigned to participate in conventional arithmetic instruction program; other member of the pair participated in a computer-assisted arithmetic program. At the end of school year, it was found that arithmetic achievement scores of students who participated in computer-assisted arithmetic program were considerably higher than those of the other sample of students.