A company selling wedding services needs to take into account the difference in age of the two partners when marketing its services. The graph shows the ages of both men and women at first marriage (www.census.gov):

Clearly, the pattern for men is similar to the pattern for women. But are the two lines getting closer together?

Here is a timeplot showing the difference in average age (men’s age – women’s age) at first marriage, the regression analysis, and the associated residuals plot:

Dependent variable is: Age Difference

R-squared = 74.9% s = 0.2346

Variable                           Coeff

Constant......................32.9679

Year............................–0.01549

a) What is the correlation between Age Difference and Year?

b) Interpret the slope of this line.

c) Predict the average age difference in 2020.

d) Compute the Durbin-Watson statistic and comment.

e) Describe reasons why you might not place much faith in that prediction.

Transcribed Image Text:

29 27 25 23 1890 1910 1930 1950 1970 1990 2010 Year Age at First Marriage (years) 21 3.85 3.10 2.35 + 1.60 1880 1910 1940 1970 2000 Year 0.4 0.2 0.0 -0.2 2.0 2.5 3.0 3.5 Predicted (M-W) Residuals Men's Age - Women's Age (years)