Question

A study on heart health was conducted where people were selected using an SRS from the city of Framingham (in the US). Researchers were mainly interested in systolic blood pressure since this is a predictor of various heart problems. The researchers also measured several other variables including sex and cholesterol level. You will investigate these variables and the relationships between them.

1) For each variable listed above, is it an explanatory variable or a response variable? Is it qualitative or quantitative? (you may want to google what systolic blood pressure is)

2) Is this an observational study or an experiment? What are the individuals in this study? What is the study population? What do you think is the target population?

3) Give an example of a lurking variable in this study.

Answer 1

(1)

(i) Variable: Systolic blood pressre: Response variable. Quantitative variable, since can be measured as a numerical value.

(ii) Variable: sex: Explanatory variable. Qualitative variable, since it has got only values:Male, Female

(iii) cholesterol level: Explanatory variable. Quantitative variable since can be measured as a numerical value.

(2)

(i)

This is an observational study and not an experiment.

(ii) Individuals in this study are heart health of people

(iii) Study population: City of Framingham in US

(iv) The target population: All people

(3) A lurking variable in this study the measurement accuracy of the instrument used to measure systolic blood pressure. It is known that measurement errors occur during evaluating systolic blood pressure and this error is to be kept constant during the entire experimental process.