In the UN Human Development Report, one variable measured was x = percentage of adults who use contraceptive methods. Table 9.11 shows part of a regression analysis using y = fertility (mean number of children per adult woman), for 22 nations listed in that report. For those nations, x had a mean of 60.0 and standard deviation of 20.6.

(a) State a research question that could be addressed with this output.

(b) Report the prediction equation and find the predicted fertility when (i) x = 0, (ii) x = 100. Show how the difference between these can be obtained using the slope.

(c) Find and interpret r and r2.

(d) What do your analyses say about the question in (a)?

TABLE 9.11 Predictor Coef. Std. Error t P>|t|

Constant 6.6633 0.4771 13.97 0.000 CONTRA -0.064843 0.007539 -8.60 0.000 Source Sum of Squares df Regression 37.505 1 Residual 10.138 20 Total 47.644 21