Chapter 4 · Sampling · Slide 145/274
How Large Must the Sample Be?
The higher the desired accuracy, the larger the sample must be.
4.4 · Sample Size
Margin of Error Approach
How Large Must the Sample Be?
The higher the desired accuracy, the larger the sample must be.
± 1 %
n = (1 / 0.01)² = 100²
10.000
± 2 %
n = (1 / 0.02)² = 50²
2.500
± 5 %
n = (1 / 0.05)² = 20²
400
± 10 %
n = (1 / 0.1)² = 10²
100
Doubling the accuracy costs four times the sample.
The size does not depend on the size of the population.
Calculations show approximate values for a 95% confidence level
QUESTIONSTAR · Dr. Paul Marx
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