Sunday, March 1, 2009

Sample Means and Deviations

For any random sample (of size n) taken from a population with mean u and standard deviation H

we can say that the mean is equal to X and that the standard deviation is equal to H/sqrt(n)

That is to say, that as the sample (n) gets larger the estimate of the standard deviation will become smaller and more accurate.

Distributions of sample populations are represented by the "t-distribution" that varies in shape by sample size, and looks much like the normal curve covered earlier. As the sample size approaches the population size the t-distribution looks more and more like the normal curve, but that is tomorrow's lesson.

No comments: