Math 37 - Lecture 27
Regression Examples
Please turn in your work for the examples at the end of class.
Example 1 Finish Class Exercise from Friday.
Example 2 A subject tries to click their mouse on a circle on a computer screen, the computer records the subject's reaction time and the distance of the new circle from the old circle. Does the time depend on the distance? The Minitab output for the right hand:
The regression equation is Time = 172 + 0.262 Distance
Predictor Coef Stdev t-ratio p
Constant 171.55 35.49 4.83 0.000
Distance 0.2619 0.1838 1.42 0.171
s = 71.11 R-sq = 10.1% R-sq(adj) = 5.1%
(a) Use the computer output to find the correlation coefficient.
(b) Use the Minitab output to test whether the distance away is a signficant predictor of the reaction time (state your hypotheses, test statistic, p-value and conclusion).
Example 3
** See instructor for graphics **
(b) Look again at the scatterplot of marriage and divorce rates. The country at the point (9.7, 4.8) is the U.S. The other 13 countries are all in Europe. Explain how you think the correlation coefficient and regression equation will change if the United States is removed from the data? What is your final conclusion about the relationship between marriage rate and divorce rate?
(c) In general, where would you place a new point on a scatterplot to make the correlation coefficient as close to 1 as possible? As close to 0 as possible?