Indicate whether each of the following studies is an experiment or an observatio
ID: 3172734 • Letter: I
Question
Indicate whether each of the following studies is an experiment or an observational study. If it is an experiment, identify the independent variable and note any possible confounding variables. (a) A psychologist uses chimpanzees to test the notion that more crowded living conditions trigger aggressive behavior. Chimps are placed, according to an impartial assignment rule, in cages with either one, several, or many other chimps. Subsequently, during a standard observation period, each chimp is assigned a score based on its aggressive behavior toward a chimplike stuffed doll. (b) An investigator wishes to test whether, when compared with recognized, professional scientists, recognized, professional artists tend to be born under different astrological signs. (c) To determine whether there is a relationship between the sexual codes of primitive tribes and their behavior toward neighboring tribes, an anthropologist consults available records, classifying each tribe on the basis of its sexual codes (permissive or repressive) and its behavior toward neigh-boring tribes (friendly or hostile). (d) In a study of group problem solving, an investigator assigns college students to groups of two, three, or four students and measures the amount of time required by each group to solve a complex puzzle. (e) A school psychologist wishes to determine whether reading comprehension scores are related to the number of months of formal education, as reported on school transcripts, for a group of 12-year-old migrant children.
Explanation / Answer
a. The assignment of chimps in the treatment groups have been done randomly, therefore, following the randomization condition, an essential criterion for an experiment. This is an experiment. The independent variables are the three treatment conditions-type of cages with one, several or many other chimps. The possible confounding variable might be food provided to the chimpanzees which might have affected their aggressive behaviour score.
b. This is an observational study, where no manipulations have been done on factors-recognized professional artists and recognized professional scientists. Only astrological signs of their births were noted and compared.
c. The anthroplogist observed the behaviour of tribes, classified into two categories, towards neighbouring tribes. The point is, whether the classification was random is not clear, and moreover, no manipulation on factors-type of tribes is done. Therefore, this is an observational study, not experiment.
d. The assignment of college students to the treatment groups-two, three or four students is not done randomly. Therefore, this is also an observational study.