SD_from_CI {metaHelper}

Standard Deviation from Confidence Interval

Description

Computes the standard deviation from the confidence interval and sample size. This method is valid only for single groups and assumes the confidence interval is symmetrical around the mean. For two groups (e.g., intervention effects), use SDp_from_CIp(). For sample sizes smaller than 60, the t-distribution (parameter "t-dist") is typically used to calculate the confidence interval.

Usage

SD_from_CI(CI_low, CI_up, n, sig_level = 0.05, two_sided = TRUE, t_dist = TRUE)

Arguments

CI_low

lower limit confidence interval

CI_up

upper limit confidence interval

n

sample size

sig_level

significance level

two_sided

whether a two sided test for significance was used

t_dist

whether a t-distribution has been used to calculate the CI. See description.

Value

Standard deviation single group

References

Cochrane Handbook

See Also

SDp_from_CIp() for two groups (e.g. intervention effects).

Examples

# lower CI = -0.5, upper CI = 2, sample size = 100
SD_from_CI(-05, 2, 100)