Standard Error Calculator
Measures how precisely a sample pins down a mean or a proportion.
Standard error of the mean
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Standard error of the proportion — points
Reading this —
The formula
SE of a mean = s ÷ √n SE of a proportion = √(p(1 − p) ÷ n)
Quadrupling the sample halves the standard error.
What to watch out for
These formulas assume a random sample from a much larger population.
Frequently Asked Questions
What is a worked example?
A standard deviation of 12 with 100 values gives a standard error of 1.2. With 400 values it falls to 0.6.
Standard deviation or standard error?
Use the standard deviation to describe the data. Use the standard error when you are talking about the precision of an estimate.