Introductory Biostatistics
gives the distribution of socioeconomic status. Test to prove that there is a significant association between the mother’s age a ...
and menstrual characteristics, exogenous estrogen use, and prior pelvic surgeries (Table E6.28). For each of the two criteria, d ...
7 Comparison of Population Means If each element of a data set may lie at only a few isolated points, we have a discreteorcatego ...
In a typical situation, the null hypothesis of a statistical test is concerned with a parameter; the parameter in this case, wit ...
zatabulated value or zbtabulated value This test is referred to as theone-sample t test. Example 7.1 Boys of a certain age have ...
In the study reported in Example 7.3, blood pressure was measured from a group of women before and after each took an oral contr ...
metal concentrations (zinc, in mg/L) for both surface water and bottom water at six di¤erent river locations (the di¤erence is b ...
0.05 level; there is enough evidence to support the hypothesis ofdi¤erentmean zinc concentrations (two-sided alternative). Note: ...
d¼average di¤erence ¼ 31 12 ¼ 2 :58 mmHg sd^2 ¼ 185 ð 31 Þ^2 = 12 11 ¼ 9 : 54 sd¼ 3 : 09 SEðdÞ¼ 3 : 09 ffiffiffiffiffi 12 p ¼ 0 ...
Let’s focus on the sample of men with a high school education; investigations of other groups and the di¤erences between them ar ...
t¼ x 1 x 2 SEðx 1 x 2 Þ where SEðx 1 x 2 Þ¼sp ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 n 1 þ 1 n 2 s s^2 p¼ ðn 1 1 Þ ...
SEðx 1 x 2 Þ¼ 4 : 96 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 25 þ 1 26 r ¼ 1 : 39 It follows that t¼ 47 : 5 37 : 5 ...
t¼ ð 0 : 20 Þð 0 : 26 Þ 0 : 022 ¼ 2 : 73 The result indicates that the di¤erence is statistically significant beyond the 0.01 ...
The result indicates that the di¤erence is statistically significant beyond the 0.01 level (ata¼ 0 :01, and for a two-sided test ...
For example, a study was designed to test the question of whether cigarette smoking is associated with reduced serum-testosteron ...
In addition, mR¼ 10 ð 10 þ 10 þ 1 Þ 2 ¼ 105 and sR¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffif ...
Example 7.9 Refer to the nicotine data of Example 7.6, where measurements were taken both from a sample of infants who had been ...
DATA; INPUT GROUP $ COTININE; DATALINES; U8 ... U 111 E35 ... E 208; PROC NPAR1WAY WILCOXON; CLASS GROUP; VAR COTININE; 7.4.2 Wi ...
is the standard deviation ofRunder the null hypothesis. This normal approxi- mation applies for relatively large samples,nb20; t ...
sR¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ð 21 Þð 22 Þð 43 Þ 24 r ¼ 28 : 77 leading to ...
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