Stephen Black wrote: "One claim is that pets are good for people who like pets. Likely no myth there. Those who like to watch foreign films and do, undoubtedly find the activity rewarding; ditto for those who like broccoli and eat it. This is practically a tautology. "
I realize he used the weasel word "practically" here but I think a tautology would be "pets will be liked by people who like pets". The key is in the operationalization of the word, "good". If by "good" you mean "enjoyment of pets", that is circular. However, to say that pets have a positive effect on health is a more specific operationalization that can be tested. It is not a tautology to say that broccoli has positive health effects for everyone but, of course, it will only be eaten by those who enjoy it and, therefore, it might make more sense to limit the test (and the generalization) only to those who like broccoli. What Stephen considers the "more significant claim" is "whether pets are good for people, like them or not." This is what I consider a good example of how internal and external validity sometimes interact. It appears that, in order to increase internal validity, you need to institute a situation that is unlike what most people will experience (being given a pet whether you like it or not) which is low in external validity. What I would do to satisfy both internal and external validity is identify your population (to which you will generalize your results) as people who are interested in having a pet and then randomly assign some to have a pet and others not to (or, in a nursing home, randomly assign some pet-loving patients to interact with pets while others are assigned some non-pet treatment activity). If your outcome was enjoyment, of course those who have pets will have more enjoyment than those who do not. However, if your outcome is a physical measure of health, you can see if those pet-lovers exposed to pets have better health outcomes than those not exposed to pets. In the case of Stephen's daughter and her cat, all four things he listed are objective measurable outcomes, three of them health-related. The fact that she loves her cat is not the same as saying the cat is good for her health (or finances) as measured by the four outcomes. It is theoretically possible to love something or someone that is not "good for you" in various ways (supply your own examples here taken from the long history of human experience or note the lyrics of this song: http://tinyurl.com/286rwkw). Rick Dr. Rick Froman, Chair Division of Humanities and Social Sciences Professor of Psychology Box 3055 John Brown University 2000 W. University Siloam Springs, AR 72761 [email protected] (479)524-7295 http://tinyurl.com/DrFroman "The LORD detests both Type I and Type II errors." Proverbs 17:15 --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=7684 or send a blank email to leave-7684-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
