ci.mad1 {statpsych}

Confidence interval for a single mean absolute deviation

Description

Computes a confidence interval for a population mean absolute deviation from the median (MAD). The MAD is a robust alternative to the standard deviation.

Usage

ci.mad1(alpha, y)

Arguments

alpha

alpha level for 1-alpha confidence

y

vector of scores

Value

Returns a 1-row matrix. The columns are:

• Estimate - estimated mean absolute deviation

• SE - standard error

• LL - lower limit of the confidence interval

• UL - upper limit of the confidence interval

References

Bonett DG, Seier E (2003). “Confidence intervals for mean absolute deviations.” The American Statistician, 57(4), 233–236. ISSN 0003-1305, doi:10.1198/0003130032323.

Examples

y <- c(30, 20, 15, 10, 10, 60, 20, 25, 20, 30, 10, 5, 50, 40, 
       20, 10, 0, 20, 50)
ci.mad1(.05, y)

# Should return:
# Estimate       SE       LL       UL
#     12.5 2.876103 7.962667 19.62282