Using
one margin of error for multiple comparisons
To
avoid calculating a separate margin of error for each response category, it is common to
calculate the most conservative standard error of a proportion (p=.5) and use this to
represent the margin of error for all response options within a specific subgroup. In the table below, a separate margin of error is
calculated for the total sample, the male sample, and the female sample.
Summary
Table
Using
one confidence interval (CI) for all data in one subgroup
(Source: GSS: Random sample of 1496 US Adults in 1993) |
|
|
|
|
|
All |
Male |
Female |
Total
Count |
1496 |
641 |
855 |
95%
CI (+/-) |
2.5% |
3.9% |
3.4% |
Respondent's
highest degree |
|
|
|
<
High school |
18.6% |
19.5% |
18.0% |
High
school |
52.1% |
47.4% |
55.7% |
Junior
college |
6.0% |
5.8% |
? 6.2% |
Bachelor |
15.6% |
16.8% |
14.7% |
Graduate |
?
7.6% |
10.5% |
? 5.4% |
I am 95% confident the percent of U.S. adults
with a junior college education level is between 3.5% and 8.5% (6.0% +/- 2.5%).
? I am 95% confident the percent of Female U.S.
adults with a junior college education level is between 2.8% and 9.6% (6.2% +/- 3.4%).
?
I am 95% confident the percent of U.S. adults
with a graduate education level is between 5.1% and 10.1% (7.6% +/- 2.5%).
?
I am 95% confident the percent of U.S. adults
with a graduate education level is between 2.0% and 8.8% (5.4% +/- 3.4%).
|
