How it works
Express how many standard deviations an observation lies above or below a mean. Standard deviation must be positive.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Observation | 85 | Enter a numeric value. |
| Mean | 70 | Enter a numeric value. |
| Standard deviation | 10 | Enter a numeric value. 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.
- Observation
- 85
- Mean
- 70
- Standard deviation
- 10
Complete example results
- Result
- 1.5
Reading the result
Check the probability scale, sample size and assumptions stated by the method. A decimal probability of 0.5 represents 50%. Mean and spread inputs must describe the same dataset; the calculation does not validate those estimates.
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.
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.