Buster runs an experiment in which she finds that participants placed in a good mood by a happy film clip are more likely to offer to a fellow participant than participants who see a sad film clip. gob suggests that perhaps this difference simply results from the fact that the participants in the happy film clip condition were more people to begin with. what methodological aspect of a successful experiment can buster point to in order to refute this criticism?

In psychological studies, random assignment refers to the use of procedures that guarantee that each participant has the same probability of assignment or choice in the study groups.

It is necessary to take into account that random assignment and random selection are different, since the first refers to the distribution of participants in random and balanced ways in experimental groups and the second refers to the selection of individuals capable of representing certain characteristics of a population

Answer

The experimental methodological aspect that Buster can point out to refute that criticism is the random assignment, whereby study participants are randomly assigned to different groups.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."