G12.22

Calcium supplementation. Consider the setting of 12.21.

1. Calculate summary statistics for the groups described in 12.21.
2. Test the mean difference for significance.

Independent Samples Test Levene's Test for Equality of Variances i-test for Equality of Means 95% Confidence Interval of the Mean Std. Error Difference F Sig. df Sig. (2-tailed) Difference Difference Lower Upper CHOL Equal variances assumed 1.999 0.175 3.282 17 0.004 0.778 0.2369 0.2776 1.2772 Equal variances 2.877 8.610 0.019 0.778 0.2702 0.1619 1.3928 not assumed FIGURE 12.3 SPSS Independent t procedures output, cholesterol illustrative data. Output includes results for Levene's test of equal variance (Ho: 012 - 2?), which is explained in Section 13.5. Graph produced with SPSS for Windows, Rel. 11.0.1.2001. Chicago: SPSS Inc. Reprint Courtesy of International Business Machines Corporation.30 20 O 10 DELTA 0 - -10 -20 10 11 Calcium Placebo GROUP The plot shows that the calcium treated group had a greater average decline in blood pressure. They also exhibited greater variability. There is a high outside value in the placebo group