Determine the confidence level
Find the critical value
Identify the standard deviation or sample proportion
Determine the sample size
Use the formula: Margin of Error = Critical Value × Standard Error
For a population mean: Standard Error = standard deviation ÷ square root of sample size
For a population proportion: Standard Error = square root of [p × (1 – p) ÷ sample size]
Multiply the critical value by the standard error
Report the result as the margin of error