Identify the major threat to internal validity in the following research studies. A researcher used two classrooms in an experimental study. It was found that the E group had more high ability students than the C group before the study began.
a. Regression
b. Diffusion
c. Mortality
d. Selection
e. History
Ques. 2Which would be the least appropriate way to assign subjects to experimental groups?
a. Rolling a die c. Teacher assignment
b. Flipping a coin d. Using a table of random numbers.
Ques. 3A researcher wants to investigate the effectiveness of three versions of a computer-assisted instructional (CAI) program in math on the achievement of elementary school students in math. The researcher wants to know if the effectiveness of the program would depend on the math aptitude (classified as above and below average) and the gender of the students. What experimental design would you recommend for this study?
a. 1 x 2 x 3 factorial design
b. 3 x 2 x 2 factorial design
c. Solomon three-group design
d. Randomized subjects, pretest-posttest, control group design
e. None of these is true.
Ques. 4In an experiment, a researcher believes that by manipulating Variable A he can cause changes in Variable B. However, Variable C is actually causing changes in Variable B. Variable C is a(n) ____ variable.
a. independent c. extraneous
b. dependent d. attribute
Ques. 5In an experimental study using pre- and posttests, which of the following instruments is most likely to have a reactive effect?
a. Arithmetic pretest
b. Scholastic aptitude test used for matching purposes
c. Film showing prejudice toward minorities
d. Divergent thinking pretest
Ques. 6The variable upon which the effects of the experimental treatment are observed is called the ____variable.
a. independent c. extraneous
b. dependent d. control
Ques. 7The difference between the group means in a pretest-posttest control group experimental design can be tested for statistical significance most precisely by
a. analysis of variance of the groups' means on the posttest.
b. separate t-tests of the prepost difference for the experimental and for the control group.
c. analysis of covariance on the groups' posttest means with pretest as the covariate.
d. analysis of variance of the mean changes from pre- to posttest for the two groups.
Ques. 8Which of the following is not a characteristic of an experiment in its simplest form?
a. A dependent variable is manipulated.
b. All variables except the independent variable are held constant.
c. The effect of manipulating the independent variable is observed.
d. Extraneous variables are controlled.
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