- Standard error is a measurement which determines the accuracy of results according to 95% confidence.

n = sample size
- It is calculated by dividing the Standard Deviation of the mean by the square root of the sample size
- The 95% confidence interval allows the results to have:
- The true mean value of the results from which the sample was taken lies between the upper and lower confidence limit
- If the intervals of two calculated means do not overlap, then the results are 95% confident that these means are different