Question

In a study published in the July 4, 2007, issue of the Journal of the American Medical Association, researchers investigated whether small doses of dark chocolate can reduce blood pressure for people who suffer from mild cases of high blood pressure. They recruited 44 German adults who were otherwise healthy except for mild cases of high blood pressure. These subjects were randomly assigned to either a dark chocolate group or a white chocolate group, and all subjects were instructed to eat one square portion of a chocolate bar (containing about 30 calories) every day for 18 weeks. They were also instructed not to eat any other cocoa products. Each subject had his/her blood pressure recorded at the beginning and end of the study, with the reduction in blood pressure calculated. It turned out that those in the dark chocolate group had an average reduction of about 3 points in systolic blood pressure, compared to a 0 point reduction on average in the white chocolate group.

Identify the response variable in this study, and classify it as categorical or quantitative.

Answer 1

Change in blood pressure ;

Quantitative

Explanation:

The response variable also called the predicted variable is the measured variable whose out one depends or relies on the value of the independent or predictor variable. In the scenario above, the measured variable is the change in blood pressure which could be caused by consumption of a certain color of chocolate. The type of chocolate consumed by the subjects (dark or white) is the independent or predictor variable which is expected to effect a change in blood pressure (predicted or measured variable).

Blood pressure change is measured using devices which output numeric values signifying the blood pressure value. This numeric characteristics makes blood pressure change a quantitative variable