Researchers Katherine Tucker and associates wanted to determine whether consumption of cola is associated with lower bone mineral density. They looked at 1125 men and 1413 women in the Framingham Osteoporosis Study, which is a cohort that began in 1971. The first examination in this study began between 1971 and 1975, with participants returning for an examination every 4 years. Based on results of questionnaires, the researchers were able to determine cola consumption on a weekly basis. Analysis of the results indicated that women who consumed at least one cola per day (on average) had a bone mineral density that was significantly lower at the femoral neck than those who consumed less than one cola per day. The researchers did not find this relation in men.


What is the response variable in this study? What is the explanatory variable?

Verified step by step guidance

1. Identify the response variable as the main outcome that the researchers are measuring to see if it changes based on other factors. In this study, the researchers are interested in bone mineral density, specifically at the femoral neck, so the response variable is the bone mineral density.
2. Identify the explanatory variable as the factor that might explain or influence changes in the response variable. Here, the researchers are examining whether cola consumption affects bone mineral density, so the explanatory variable is the amount of cola consumed (measured as at least one cola per day versus less than one cola per day).
3. Understand that the response variable is typically the dependent variable in a study, which is affected by the explanatory variable, the independent variable.
4. Summarize: The response variable is the bone mineral density at the femoral neck, and the explanatory variable is the level of cola consumption (categorized by frequency).
5. Recognize that this setup allows researchers to analyze if differences in cola consumption are associated with differences in bone mineral density, which is the core relationship being studied.

Key Concepts

Response Variable

The response variable is the outcome or dependent variable that researchers measure to see the effect of changes in another variable. In this study, it is the bone mineral density, as the researchers want to see how it varies with cola consumption.

Explanatory Variable

The explanatory variable, also called the independent variable, is the factor that is believed to influence or explain changes in the response variable. Here, it is the amount of cola consumption, categorized by frequency, which may affect bone mineral density.

Cohort Study Design

A cohort study follows a group of people over time to observe how certain exposures affect outcomes. This study uses the Framingham Osteoporosis cohort, tracking cola consumption and bone density over years, allowing researchers to assess associations longitudinally.