AAMC FL2 #56 (PS)

[663697]

This is more of a general question regarding research methods; can a study be experimental and correlational at the same time? The passage referred to a study where smokers were randomly assigned into a control and experimental (yoga) group in order to determine the efficacy of yoga as a smoking cessation therapy and were followed over some months.

The fact that they were randomly assigned to 2 groups and followed over a period of time shows that it is both experimental and longitudinal, but for some reason I couldn't bring myself to believe that it was correlational as well. Isn't the whole point of an experiment to infer causality? Why would we need a correlational study when we've already done an experiment?

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[663697]

For context:

 

[Nugester]

I'm not sure what you mean "already done" an experiment? They do use correlation because they are trying to find the association between yoga and smoking cessation.

 

[663697]

I'm not sure what you mean "already done" an experiment? They do use correlation because they are trying to find the association between yoga and smoking cessation.

I mean that the objective was to find if yoga has an effect on smoking cessation. At least from what I've read in my review book, conducting an experiment allows you to infer causality between the variables, while a correlational study only tells you there's a correlation, and that there may be other variables involved that have not been taken into account. If you already determined causality between yoga and cessation therapy in your experiment, why would you also call it correlational?

 

[Nugester]

I see what you are saying. I see it as

Longitudinal - because it is done over 3-6 months
Experimental - because there are control and groups and independent/dependent variables
Correlation - because they are comparing the association between above variables

You might say it is redundant but if two answers state/measure the same thing you can't really eliminate one or the other. Also, for an observational study, researchers CAN'T control which groups people go into.

So weakest choice would be A.

 

[663697]

This is a similar question so I thought I'd just post it here. The answer makes sense here but I was just wondering why the non-modified and modified mice weren't randomly assigned to their respective groups. Since it doesn't state it, is it implied that they already randomly assigned them to the non-modified/modified groups?

 

[Nugester]

Are you asking whether the control mice were randomly put into non-modified and modified groups?

In practice, a lot of labs commercially purchase their mice because they are bred over time; control mice are automatically in the control group and the engineered mice are in the experimental group. If the lab does all that work themselves, then yes, I would imagine the researchers randomly selected the control mice to be put in the control group and the others in the experimental group.