Convert between standard deviation, standard error and confidence interval of a mean, using t or z, following the Cochrane Handbook formulas.
About this tool
Convert between standard deviation, standard error and confidence interval.
How to use SD, SE & CI Converter
- Choose whether you have the SD, the SE or a confidence interval.
- Enter the mean, the sample size and the value you have.
- Read the other two measures.
Worked example
A mean of 52.3 with a 95% CI of 48.8 to 55.8 from 25 people gives an SE of 1.70 and an SD of 8.48 using the t distribution.
When should I use t rather than z?
The Cochrane Handbook recommends t for samples under about 60, because the interval was probably calculated with t.
Can I use this for odds ratios?
No. Ratio intervals are symmetric on the log scale, so use the meta-analysis effect converter.
References
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