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AMERICANS' KNOWLEDGE OF THE U.S. CONSTITUTION
A Columbia Law Survey
May 2002

Conducted by       

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RELIABILITY OF SURVEY PERCENTAGES

Results of any sample are subject to sampling variation. The magnitude of the variation is measurable and is affected by the number of interviews and the level of the percentages expressing the results.

The table below shows the possible sample variation that applies to percentage results reported from Opinion Research Corporation's CARAVAN sample. The chances are 95 in 100 that a CARAVAN survey result does not vary, plus or minus, by more than the indicated number of percentage points from the result that would be obtained if interviews had been conducted with all persons in the universe represented by the sample.

Size of Sample on 
Which Survey 
Results Are Based

Approximate Sampling Tolerances Applicable
to Percentages At or Near These Levels
10% or 90% 20% or 80% 30% or 70% 40% or 60% 50%
2,000 interviews 1% 2% 2% 2% 2%
1,000 interviews 2% 2% 3% 3% 3%
500 interviews 3% 4% 4% 4% 4%
250 interviews 4% 5% 6% 6% 6%
100 interviews 6% 8% 9% 10% 10%

 

Additional Sampling Tolerances for Samples of 1,000 Interviews
9% or 91%
2%
8% or 92%
2%
7% or 93%
2%
6% or 94%
1%
5% or 95%
1%
4% or 96%
1%
3% or 97%
1%
2% or 98%
1%
1% or 99%
.2%

 

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