Russel-Research-Method-in-Anthropology

Univariate Analysis 583
TABLE 19.10
How to Calculate the Standard Deviation for the Data on Female Illiteracy in Table 19.7
FEMILLIT
COUNTRY x (x x) 2
Armenia 2.4 (2.4 19.49) 2 292.07
Chad 66.0 (66.0 19.49) 2 2,163.18
El Salvador 23.8 (23.8 19.49) 2 18.58
Ghana 37.1 (37.1 19.49) 2 310.11
Iran 30.1 (30.1 19.49) 2 112.57
Latvia 0.2 (0.2 19.49) 2 372.10
Namibia 18.8 (18.8 19.49) 2 .48
Panama 8.7 (8.7 19.49) 2 116.42
Slovenia 0.4 (0.4 19.49) 2 364.43
Suriname 7.4 (7.4 19.49) 2 146.17
x x 2 3,896.11
s 3896.11/9 20.81
Substituting in formula 19.6 for sd, we get:
s
5,800
29 14.14
and we report that ‘‘the mean age is 45.00, sd 14.14.’’ For comparison, the
mean age and sd of the 30 ages (the ungrouped data) in table 19.3b are 45.033
and 15.52. Close, but not dead on.
Are these numbers describing ages and percentages of illiteracy large, or
small, or about normal? There is no way to tell except by comparison across
cases. By themselves, numbers like means and standard deviations simply
TABLE 19.11
Calculating the Standard Deviation for the Grouped Data in Table 19.4
AGE X f Midpoint x x x (x x) 2 f(x x) 2
20–29 6 25 25 45 20 400 2,400
30–39 6 35 35 45 10 100 600
40–49 5 45 45 45 0 0 0
50–59 8 55 55 45 10 100 800
60 5 65 65 45 20 400 2,000
x 30 (x x) 0 f(x x) 2 5,800