How it works
For two independent groups, s1²/n1 and s2²/n2 are added before taking their square root. This form solves for standard error of the difference; enter the known quantities in First group sample deviation, First group size, Second group sample deviation, Second group size.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| First group sample deviation | 3 | Formula symbol: s1. Enter a numeric value. Must be greater than zero. |
| First group size | 18 | Formula symbol: n1. Enter a numeric value. Use a whole number. Must be greater than zero. |
| Second group sample deviation | 3 | Formula symbol: s2. Enter a numeric value. Must be greater than zero. |
| Second group size | 18 | Formula symbol: n2. Enter a numeric value. Use a whole number. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- First group sample deviation
- 3
- First group size
- 18
- Second group sample deviation
- 3
- Second group size
- 18
Complete example results
- Standard error of the difference
- 1
Reading the result
The result solves for standard error of the difference from the entered quantities. Check the result unit and the formula conditions before using it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
When can I use the standard error of the difference result?
Groups must be independent and deviations use the same unit. Paired observations need deviation of differences. The n solution rounds its threshold up; no p-value is computed.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: itl.nist.gov