Question

A sample of 548 ethnically diverse students from Massachusetts were followed over a 19 -month period from 1995 and 1997 in a study of the relationship between TV viewing and eating habits (Pediatrics [2003]: 1321- 1326). For each additional hour of television viewed per day, the number of fruit and vegetable servings per day was found to decrease on average by \(0.14\) serving. a. For this study, what is the dependent variable? What is the predictor variable? b. Would the least-squares line for predicting number of servings of fruits and vegetables using number of hours spent watching TV as a predictor have a positive or negative slope? Explain.

Short answer

a. The dependent variable is the number of servings of fruit and vegetables per day and the predictor variable is the number of hours of television viewed per day. b. The slope of the line would be negative because as the number of hours of television viewed increases, the servings of fruit and vegetables decrease.

Step-by-step solution

Identifying Variables

The dependent variable is the one that is the 'outcome' or the variable that we want to predict or estimate. The independent or predictor variable is the one that affects the dependent variable. In the given problem, the dependent variable is the number of fruit and vegetable servings per day as this is what we want to predict or estimate and the predictor variable is the number of hours of television viewed per day, as this is the variable that affects the fruit and vegetable intake.

Identifying the Slope of the Line

The slope of the least-squares line is based on the relationship between the dependent and independent variables. The problem states that for each additional hour of television viewed per day, the number of fruit and vegetable servings per day decreases by 0.14. This indicates a negative relationship. Therefore, the slope of the line would be negative.