# Standard Deviation algorithm for small population size?

I need to calculate the standard deviation on the entire population. The population size is 7, but for others it may be between 5-14. I see a few variance algorithms listed on Wikipedia. What stdev algorithms should I use for this population size?

• Your question is not really clear. – smanoos Dec 31 '11 at 20:32
• The formula will not change, only the reliability of your estimate. Are you asking for 'variance of tge variance' formulas? – gnometorule Dec 31 '11 at 20:50
• I was just wondering if I should square root the two-pass variance algorithm or the naive variance algorithm? Or if there was something else that would provide me with a more accurate estimate for small population sizes? I see warnings about using certain techniques for large population sizes and was just wondering if there was any problem w/ small population sizes. – Bradford Dec 31 '11 at 21:06

Much more importantly to avoid a common error, since you have the whole population you should always divide by the population size $n$ rather than $n-1$ (using $n-1$ might make sense if you only had a sample, could not find the population mean, and wanted an unbiased estimate of the population variance).