To research the effects of dietary patterns on blood...

To research the effects of "dietary patterns" on blood pressure in 459 subjects, subjects were randomly assigned to three groups and had their meals prepared by dieticians. Those who were fed a diet low in fat and cholesterol and high in fruits, vegetables, and low-fat dairy foods (known as the DASH diet) lowered their systolic blood pressure by an average of 6.7 points when compared with subjects fed a control diet. a) Explain why this is an experiment and not an observational study. b) Identify the subjects. c) Identify the factor(s) in the experiment and the number of levels for each. d) How many treatments are there? e) What is the response variable? Units? f) What was the conclusion of the study?

Transcript

00:01 In letter a, we need to explain why this is an experiment and not an observation study.

00:07 So the key here to explain this is, in this case, because the study, so we can put like the study has used randomization here.

00:26 So we can put this here to assign this subject.

00:31 Into groups.

00:35 So this here is a characteristic of an experiment and this is an experiment instead of like observation study because instead of just observing the result like asking those people about their systolic blood pressure these the researchers had conduct like our randomization, which consists in separate the subjects randomly into three groups.

01:09 And then by each group being assigned a different treatment, in this case our different diets, then they will like compare the systolic blood pressure for which each one of these two, these three groups in this case.

01:26 So as you can see, the researcher has a control by randomizing the observations into groups instead of only observing the blood pressure of this individual.

01:41 So that's why, because of this randomization, that we have an experiment.

01:45 Now in letter b we need to identify the subjects.

01:49 Here we have a total of 469 subjects and we can even put, because we don't have a lot of information about them, we can say that these subjects received a specific in this case in the study diet here.

02:11 So this subject depending on their group, they would like receive a specific diet.

02:18 But the important thing to put in letter b is the amount of people that we are considering.

02:24 Now in letter c, we need to identify the factor of factors in the experiment and the number of levels for each.

02:32 So in this case we have a one factor which is the diet and the diet has three levels in this case which you are given by there is one that is the control...

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