where:
s = standard deviation of sample
= mean of sample
n = sample size
Links on confidence interval of mean and standard error
Dear All
I have been asked to present some information from a series of published articles according to Mean (+/- 95% Confidence Interval).
The statistical summaries are generally presented as:
Number of subjects (n)
Mean (X)
Standard deviation of the mean (sd)
How do I calculate the 95% confidence intervals from just this information? Do I need the actual raw data??
Thanks, best wishes
David
where:
s = standard deviation of sample
= mean of sample
n = sample size
Links on confidence interval of mean and standard error
"If you torture the data long enough it will eventually confess."
-Ronald Harry Coase -
drhealy (01-13-2012)
Note that this is technically if you knew the population standard deviation. Since it sounds like this is being computed from the data you should probably use whatever the corresponding t-quantile is instead of 1.96. But if your sample size is large enough it will be close enough to essentially not matter.
To clarify; I am compiling a data chart summarizing a lot of very small studies (eg. n of 30).
eg. study A of 30 subjects found a mean of 20.2 with an sd of 6, study B of 42 subjects found a mean of 27 with an sd of 4, etc.
How do I find /calculate the t-quantile to place into the calculation?
look it up in chart (CHART LINK HERE) or use a program/calculator. Excel will figure it out for you (LINK)
"If you torture the data long enough it will eventually confess."
-Ronald Harry Coase -
drhealy (01-13-2012)
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