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Confidence interval for a mean

Source: R/statpsych1.R
ci.mean.Rd

Computes a confidence interval for a population mean using the estimated mean, estimated standard deviation, and sample size. Use the t.test function for raw data input.

Usage

ci.mean(alpha, m, sd, n)

Arguments

alpha

alpha level for 1-alpha confidence

m

estimated mean

sd

estimated standard deviation

n

sample size

Value

Returns a 1-row matrix. The columns are:

  • Estimate - estimated mean

  • SE - standard error

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

References

Snedecor GW, Cochran WG (1989). Statistical Methods, 8th edition. ISU University Pres, Ames, Iowa.

Examples

ci.mean(.05, 24.5, 3.65, 40)
#>  Estimate        SE       LL       UL
#>      24.5 0.5771157 23.33267 25.66733

# Should return:
# Estimate        SE       LL       UL
#     24.5 0.5771157 23.33267 25.66733