In Exercises 21–28, determine whether the study is an experime...

Question

In Exercises 21–28, determine whether the study is an experiment or an observational study, and then identify a major problem with the study.

Atkins Weight Loss Program An independent researcher tested the effectiveness of the Atkins weight loss program by randomly selecting 1000 subjects using that program. Each of the subjects was called to report their weight before the diet and after the diet.

Accepted Answer

All right, hello, everyone. So, this question is asking us to determine whether the following study is an experiment or an observational study, and identify a significant issue with the study. The effectiveness of a new fitness program was evaluated by randomly selecting 800 participants already enrolled in the program. The participants reported their weight both before starting and after completing the program. And here we have 4 different entry choices labeled A through D, proposing whether or not it's an experiment or an observational study, and proposing the main issue with the given study. So first, what is an experiment? Versus an observational study. What does it mean for a study to be one versus the other? Well, for me, the key word is observation or observational. Right, because in an observational study, the job of the researcher. Is to observe. And record Right The researchers are not doing anything to potentially impact the outcome of whatever it is they are observing. But on the other hand, an experiment is divined or defined rather. By the manipulation. Of at least one variable. It could be multiple. So in an experiment, the researcher is deliberately manipulating one or more variables to observe their effects on the outcome that they are studying. So here The main thing to recognize about this specific example is that the participants are already part of the program that's included in the study. So therefore, the researchers aren't necessarily assigning participants to different groups, or in other words, controlling any variables. For example, The researchers aren't necessarily assigning participants. To either complete the program or not complete the program. So therefore, this is going to count as an observational study, because again, the participants aren't being assigned to different groups. So, the fact that they're not being assigned to different groups also introduces the main issue with the study, right? Because here, the goal of the study is to evaluate the effectiveness of the program. So, to understand the effectiveness of the program, you would need a control, right? How do participants of the program compare relative to people that were not participating in the program? In this case, there's no control group, which means that you can't compare the results of the program against people that did not participate in it. So therefore, it's difficult to decide whether or not the weight changes among participants are due to the fitness program itself or other factors. So therefore, the answer is going to be option C in the multiple choice. Not only because this is an example of an observational study. But because the major issue with the study is that there is no control group to compare results. And there you have it. So with that being said, thank you so very much for watching, and I hope you found this helpful.

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Key Concepts

Experimental Study

Observational Study

Random Sampling

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