SEM Calculator
Calculate the Standard Error of the Mean
About Standard Error of the Mean
The Standard Error of the Mean (SEM) measures how precisely the sample mean estimates the population mean. It decreases as sample size increases.
Formula: SEM = s / √n
Where s is the sample standard deviation and n is the sample size.
Key Points:
- SEM is always smaller than the standard deviation
- Larger samples produce smaller SEM (more precise estimates)
- SEM is used to construct confidence intervals for the mean
- Quadrupling the sample size halves the SEM