Comprehensive Calculator Guide
This calculator works out the standard error of the mean, the sample SD divided by √n, and the relative standard error, showing how precisely a sample mean estimates the population mean. Eight marks with mean 83.1 and SD 11.3 give an SE of 4.0.
SE vs SD
The SD describes individuals; the SE describes the mean and shrinks with sample size: four times the data halves it. A rough 95% interval is mean ± 2 SE for large samples.
How to Use
- Enter the sample data.
- At least two values.
- Press “Calculate” to see the SE, mean, SD and RSE.
Formula Used
SE = s ÷ √n | RSE = SE ÷ mean × 100%
Practical Examples
- Example 1
- Marks: SE ≈ 4.0.
- Example 2
- Reaction times: SE ≈ 0.0069 s.
Important Tips
- Report n with the SE.
- Quadruple n to halve it.
- SD for people, SE for the mean.
Common Mistakes to Avoid
- Reporting SE as SD.
- Dividing by n.
- Using ±2 SE for tiny samples.
Frequently Asked Questions
- SE vs SD?
- SE is the mean’s precision.
- How is it calculated?
- s ÷ √n.
- 95% interval?
- About mean ± 2 SE.