Effect of Sample Size

BHS Statistics

Effect of Sample Size on Variability amongst Samples

September 7, 1999

The attached pages show collections of 2500 random samples. One collection contains samples of size 100. The other collections contain samples of sizes 200 400, 800, 1600, and 3200. Every sample was taken from a large population having .32 of it believing "yes" on a subject. (Each sample was replaced before selecting another). Use the attached sheets to complete this table.

Number of samples drawn: 2500

Population Percent: 0.32 (32%)

Sample Size
Percent of Sample Percents within 1 percentage point of Population Percent
Percent of Sample Percents within 2 percentage points of Population Percent
Percent of Sample Percents within 3 percentage points of Population Percent
Percent of Sample Percents within 4 percentage points of Population Percent

100

200

400

800

1600

3200

After completing the table:

What can you say about variability amongst samples of a given size in relation to sample size per se?

2500 Samples, each sample having 100 individuals

2500 Samples, each sample having 200 individuals

2500 Samples, each sample having 400 individuals

2500 Samples, each sample having 800 individuals

2500 Samples, each sample having 1600 individuals

2500 Samples, each sample having 3200 individuals

Sample Size	Percent of Sample Percents within 1 percentage point of Population Percent	Percent of Sample Percents within 2 percentage points of Population Percent	Percent of Sample Percents within 3 percentage points of Population Percent	Percent of Sample Percents within 4 percentage points of Population Percent
100
200
400
800
1600
3200