simple random sample
it is a sample without replacement, and
the probability of picking this sample is equal to the probability of picking any other sample of size from the same population .
From the first part of the definition, there are
samples of items from a population of items. From the
second part of the definition, the probability of any sample of size
in is a constant. Therefore, the probability of picking a
particular simple random sample of size from a population of
size is .
Remarks Suppose are values representing the items sampled in a simple random sample of size .
The variance of the sample mean from the true mean is
The larger the sample size, the smaller the deviation from the true population mean. When , the variance is the same as the true population variance.
|Title||simple random sample|
|Date of creation||2013-03-22 15:13:01|
|Last modified on||2013-03-22 15:13:01|
|Last modified by||CWoo (3771)|