The accompanying data were read from a plot (and are a subset of the complete data set) given in the article Cognitive Slowing in Closed-Head

The accompanying data were read from a plot (and are a subset of the complete data set) given in the article €œCognitive Slowing in Closed-Head Injury€ (Brain and Cognition [1996]: 429€“ 440). The data represent the mean response times for a group of individuals with closed-head injury (CHI) and a matched control group without head injury on 10 different tasks. Each observation was based on a different study, and used different subjects, so it is reasonable to assume that the observations are independent.

a. Fit a linear regression model that would allow you to predict the mean response time for those suffering a closed-head injury from the mean response time on the same task for individuals with no head injury.
b. Do the sample data support the hypothesis that there is a useful linear relationship between the mean response time for individuals with no head injury and the mean response time for individuals with CHI? Test the appropriate hypotheses using a = .05.
c. It is also possible to test hypotheses about the y intercept in a linear regression model. For these data, the null hypothesis H0: a = 0 cannot be rejected at the .05 significance level, suggesting that a model with a y intercept of 0 might be an appropriate model. Fitting such a model results in an estimated regression equation of CHI = 1.48(Control) Interpret the estimated slope of 1.48.

Mean Response Time Study Control CHI 250 360 475 525 610 740 880 920 1010 1200 303 491 659 683 922 1044 1421 1329 1481 1815 6 10