A story at ABCNews ("Pet Contact" by Rita Rubin, March 17, 1998) reported that Karen Allen, a researcher at the University of Buffalo, found that couples who own cats or dogs have more satisfying marriages and are less stressed out than those who don’t own pets. Pet owners also have more contact with each other and with other people. Allen compared 50 couples who owned either cats or dogs with 50 petfree couples. The volunteers completed a standard questionnaire assessing their relationship and how attached they were to their pets. They also kept track of their social contacts over a 2-week period. To see how the couples responded to stress, Allen monitored their heart rates and blood pressure while they discussed sore subjects. Pet-owning couples started out with lower blood pressure readings than the others, and their numbers didn’t rise as much when they argued.
a. Was this a case–control study, a randomized experiment, or an observational study that was not case–controlled?b. What are the explanatory and response variables in this study?c. Give an example of a possible confounding variable.