In Exercises 9 and 10, determine whether the study is an obser...

Question

In Exercises 9 and 10, determine whether the study is an observational study or an experiment. Explain.

To study the effect of using digital devices in the classroom on exam performance, researchers divided 726 undergraduate students into three groups, including a group that was allowed to use digital devices, a group that had restricted access to tablets, and a control group that was “technologyfree.” (Source: Massachusetts Institute of Technology)

Accepted Answer

Hi, everyone, let's take a look at this practice problem. This problem says a nutritionist wants to determine if a new diet plan helps people lose weight more effectively than a standard diet. She randomly assigns 150 participants to either the new diet plan or the standard diet and tracks their weight loss over 3 months. Is this study an observational study or an experiment? Explain your answer. And we're given 4 possible choices as our answers. For choice A, an observational study because the nutritionist is observing the participants over time. For choice B, an observational study because the participants are following a diet plan. For choice C, an experiment because the nutritionist is manipulating the type of diet the participants follow, randomly assigning them to groups and tracking the outcome over time. And for choice D, an experiment because the nutritionist assigns a sufficiently large number of participants. Now we need to determine whether the study here is an observational study or an experiment. And that recall for an experiment, researchers actively intervene and manipulate one or more variables to see the effects of an outcome variable. So, in this case, the nutritionist is manipulating the type of diet that the participants follow, since they need to either follow the new diet plan or the standard diet. And the type of diet is going to be the independent variable for our study. She is also randomly assigning the participants into two different groups. And this random assignment is important because it helps to ensure that the groups are similar at the start of the study, reducing the chance that other factors could explain any differences in weight loss. And finally, she is actually tracking the weight loss over time. And so she is observing the outcome, which in this case is our weight loss over time. And the weight loss here is our dependent variable in the study. And therefore, this study actually fits the definition of an experiment. And so, if we look at our answer choices, we see that the correct answer choice is answer choice. C. Which says, an experiment, because the nutritionist is manipulating the type of diet the participants follow, randomly assigning them to groups and tracking the outcome over time. So I hope that this explanation has been useful, and I'll see you in the next video.

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Key Concepts

Observational Study

Experiment

Control Group

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