Question 3

Skin temperature is the numerical variable in the study.

Skin temperature, as measured in degrees, is a numerical variable that can be quantified and analyzed statistically, making it the correct choice in this context.

A) Food group in a study about the eating habits of professional athletes

Food group is a categorical variable that classifies data into distinct categories such as fruits, vegetables, and grains. It does not involve numerical measurements, thus making it incorrect in identifying a numerical variable.

B) Diet in a study about food and cognitive functioning

Diet, while it may be described using various qualitative factors, does not provide numerical data and is therefore classified as a categorical variable. It is not suitable for this question regarding numerical variables.

C) Screen color in a study about visual perception

Screen color is another categorical variable, as it refers to different colors that cannot be measured numerically. This makes it an incorrect option when searching for a numerical variable.

D) Skin temperature in a study about reactions to a new medical treatment

Skin temperature is a numerical variable that can be measured in degrees. This allows for quantitative analysis and statistical evaluation, making it the correct choice in this scenario.

Conclusion

Skin temperature is definitively the correct answer as it represents a measurable quantity, unlike the other options that are categorical variables. Each of the other choices fails to meet the criteria of being numerical, highlighting the importance of distinguishing between types of variables in research.