0.05 level; there is enough evidence to support the hypothesis ofdi¤erentmean
zinc concentrations (two-sided alternative).
Note: An SAS program would include these instructions:
DATA;
INPUT BZINC SZINC;
DIFF = BZINC - SZINC;
DATALINES;
.430 .415
.266 .238
.567 .390
.531 .410
.707 .605
.716 .609;
PROC MEANS N MEAN STDERR T PRT;
for which we’ll get sample size (N), sample mean (MEAN), standard error
(STDERR),tstatistic (T), andpvalue (PRT).
Example 7.3 The systolic blood pressures ofn¼12 women between the ages
of 20 and 35 were measured before and after administration of a newly devel-
oped oral contraceptive. Data are shown in Table 7.2 (the di¤erence is after–
before). The necessary summarized figures are
TABLE 7.2
Systolic Blood
Pressure (mmHg)Subject Before After
Di¤erence,
di di^2
1 122 127 5 25
2 126 128 2 4
3 132 140 8 64
4 120 119 11
5 142 145 3 9
6 130 130 0 0
7 142 148 6 36
8 137 135 24
9 128 129 1 1
10 132 137 5 25
11 128 128 0 0
12 129 133 4 16
31 185ANALYSIS OF PAIR-MATCHED DATA 251