A researcher collects a nationally based set of data about cholesterol levels and age at first circulatory incident (myocardial infarction or cerebrovascular accident). The researcher performs a linear regression analysis in order to do which of the following?

a. Estimate the age at which circulatory incidents are likely to occur, given the cholesterol level.

b. Determine how well the data fit the theoretical framework.

c. Calculate the strength of the relationship between cholesterol levels and circulatory incidents.

d. Determine whether there is a linear relationship between cholesterol levels and circulatory incidents.

e. Derive the formula for the line of best fit.

f. Obtain information from which to construct a better scatter plot.

A researcher performs a linear regression analysis on the published national data about cholesterol levels and age at first circulatory incident. This is a form of observational study where the data is analyzed to find any patterns and to discover any relationships.

First the data might be plotted and a correlation coefficient could be calculated. If there is a linear correlation, such as increased levels of cholesterol may indicate a decrease in the age of first circulatory incident, then a linear regression would be performed to find an equation of the line of best fit to the data. This equation can be used to make predictions. The predictor variable will be the cholesterol level and the response variable is the person's age.

The result of this work will be a better method of estimating the age at which circulatory incidents are likely to occur, using a measured cholesterol level of an individual.

Answer: a. Estimate the age at which circulatory incidents are likely to occur, given the cholesterol level.