The selection-history effect is particularly a problem in which quasi-experimental design?
a. non-equivalent comparison group
b. time series
c. interrupted time series
d. regression discontinuity
Question 2
Two middle school teachers want to find which of three new violence prevention programs would be most effective in their school. From September through November, program 1 is in effect.
It is then replaced by program 2 from December through February, and then program 3 runs from March through May. In June the teachers examined fight reports for the school year and find that there were 14 fights in the fall, 10 fights in the winter, and 6 fights in the spring. They conclude that program 3 is most effective is stopping violence. Which of the following is
a plausible rival hypothesis to their interpretation?
a. fighting decreases in spring, anyway
b. the effects of programs 1 and 2 could have carried over into the spring
c. whatever program came third might have been associated with the fewest fights
d. all of the above are plausible alternative explanations
