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Confidence Level Calculator
Sample Size Calculator
Differences of percentages among two independent populations
Differences of percentages among overlapping populations
Confidence Level Calculator
This display +/- data tolerances given sample sizes and desired confidence levels
Sample Size
95%
90%
85%
80%
50
13.85%
11.63%
10.17%
9.06%
100
9.79%
8.22%
7.19%
6.40%
150
8.00%
6.71%
5.87%
5.23%
200
6.92%
5.81%
5.08%
4.53%
250
6.19%
5.20%
4.55%
4.05%
300
5.65%
4.74%
4.15%
3.69%
350
5.23%
4.39%
3.84%
3.42%
400
4.89%
4.11%
3.59%
3.20%
450
4.61%
3.87%
3.39%
3.02%
500
4.38%
3.67%
3.21%
2.86%
550
4.17%
3.50%
3.06%
2.73%
600
4.00%
3.35%
2.93%
2.61%
650
3.84%
3.22%
2.82%
2.51%
700
3.70%
3.10%
2.72%
2.42%
750
3.57%
3.00%
2.62%
2.33%
800
3.46%
2.90%
2.54%
2.26%
850
3.36%
2.82%
2.46%
2.19%
900
3.26%
2.74%
2.39%
2.13%
950
3.17%
2.66%
2.33%
2.07%
1000
3.09%
2.60%
2.27%
2.02%
Incidence (.1% to 99.9%)
% (if unsure, leave at 50)
Starting Sample Size (N=)
