The cells contain the sample size necessary to obtain the column Confidence Interval
to within the row error of the true standard deviation. For example, 84 subjects will be necessary
to obtain a 80% confidence that the standard deviation obtained is within ±10%
of the true value.
Error | 80%CI | 85%CI | 90%CI | 95%CI | 99%CI | 99.9%CI |
±1% | 8213 | 10363 | 13529 | 19208 | 33175 | 54140 |
±2% | 2054 | 2592 | 3383 | 4803 | 8295 | 13536 |
±5% | 330 | 416 | 561 | 781 | 1401 | 2167 |
±10% | 84 | 105 | 137 | 193 | 333 | 543 |
±15% | 38 | 47 | 61 | 87 | 149 | 242 |
±20% | 22 | 27 | 35 | 49 | 84 | 137 |
±25% | 15 | 18 | 23 | 32 | 54 | 88 |
The sample size in column 1 increases exponentially from 2, and the cells
show error of estimation as ± percent of true Standard Deviation
for 80%, 85%, 90%, 95%, 99% and 99.5% Confidence Intervals. for example,
with a sample size 0f 32, the 80% confidence Interval or Error is ±16.3%
of the true value
Ssize | 80%CI | 85%CI | 90%CI | 95%CI | 99%CI | 99.5%CI |
2 | 83.2 | 88.6 | 94.0 | 99.5 | 100.0 | 100.0 |
4 | 51.9 | 57.4 | 64.3 | 74.3 | 94.8 | 100.0 |
8 | 34.2 | 38.2 | 43.3 | 51.0 | 66.0 | 72.0 |
16 | 23.4 | 26.2 | 29.8 | 35.4 | 46.2 | 50.3 |
32 | 16.3 | 18.3 | 20.8 | 24.8 | 32.4 | 35.3 |
64 | 11.4 | 12.8 | 14.6 | 17.4 | 22.8 | 24.9 |
128 | 8.0 | 9.0 | 10.3 | 12.3 | 16.1 | 17.6 |
256 | 5.7 | 6.4 | 7.3 | 8.7 | 11.4 | 12.4 |
512 | 4.0 | 4.5 | 5.1 | 6.1 | 8.1 | 8.8 |
1024 | 2.8 | 3.2 | 3.6 | 4.3 | 5.7 | 6.2 |
2048 | 2.0 | 2.2 | 2.6 | 3.1 | 4.0 | 4.4 |
4096 | 1.4 | 1.6 | 1.8 | 2.2 | 2.8 | 3.1 |
8192 | 1.0 | 1.1 | 1.3 | 1.5 | 2.0 | 2.2 |
16384 | 0.7 | 0.8 | 0.9 | 1.1 | 1.4 | 1.6 |