A sample of 15 observations has a standard deviation of 4. The sum of the squared deviations from the sample mean is?
I'm stuck on this problem is you can please help me I would much appreciate it, thanx!
For a sample you must use a divisor of N-1 to have an unbiased estimation of the real standard deviation.
For a population you must use a divisor of N to get the real standard deviation.
When calculating a sample variance in the context of plain and simple univariate statistics, a divisor of N is used. The wikipedia link says this.
A key quote from the Wiki link:
"Note that if the above data set represented only a sample from a greater population, a modified standard deviation would be calculated (explained below) to estimate the population standard deviation, which would give 6.93 for this example."