Question

To investigate if there is an association between eating red meat and the health of individuals, researchers used data from a national survey of 120,000 randomly selected American adults. In the data, there was a strong association between the amount of red meat consumed and the frequency and severity of illnesses contracted.

(a) Is this an experiment or an observational study? Explain.

(b) Is it legitimate to deduce that the observed association in the data generalizes to all American adults? If yes, explain why. If not, explain why not.

(c) Is it legitimate to deduce from this study that eating red meat caused the subjects in the study to be more prone to illness? If it is, explain carefully. If not, identify a possible confounding variable explaining carefully why your variable is confounding.

Answer 1

a) Observational study

b) No

c) No

-Eating habits

-Age

-Health hystory

Explanation:

Hello!

An observational study is one where the investigator has no control or intervenes on it. He just defines the variable of interest and merely collects and documents the information. These types of studies are usually made as precursors to a more formal experimental study, to have an idea of what's to be expected from the population.

In this example, the researcher merely took the information of interest from the survey that was taken. The researcher did not intervene in any way in the experiment. Because of the lack of intervention from the researcher, it is not valid to use the conclusions of this experiment to generalize to all American adults. For instance, it is not sure that the sample is representative, all people responding to the survey may be healthy or have certain eating habits. This also shows that many confusing factors are not taken into account like:

-eating habits (from eating healthy to extreme cases like being vegetarian/vegan or eating only fast food)

-age, the age range is not defined, if the sample is taken from surveys answered by people in their early 20s it will be different in both eating habits and health information as if the interviewees are in their 30s or 40s

-before health issues, there can be other health conditions that may be affecting the interviewees.

I hope it helps!