Skip to contents

Confidence interval for the slope of medians in a one-factor experimental design with a quantitative between-subjects factor

Source: R/statpsych2.R
ci.slope.median.bs.Rd

Computes a distrbution-free test and confidence interval for the slope of medians in a one-factor experimental design with a quantitative between-subjects factor using sample group medians and standard errors as input. The sample median and standard error for each group can be computed using the ci.median function.

Usage

ci.slope.median.bs(alpha, m, se, x)

Arguments

alpha

alpha level for 1-alpha confidence

m

vector of sample median

se

vector of standard errors

x

vector of quantitative factor values

Value

Returns a 1-row matrix. The columns are:

  • Estimate - estimated slope

  • SE - standard error

  • z - z test statistic

  • p - two-sided p-value

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

Examples

m <- c(33.5, 37.9, 38.0, 44.1)
se <- c(0.84, 0.94, 1.65, 2.98)
x <- c(5, 10, 20, 30)
ci.slope.median.bs(.05, m, se, x)
#>   Estimate        SE        z           p        LL        UL
#>  0.3664407 0.1163593 3.149216 0.001637091 0.1383806 0.5945008

# Should return:
#   Estimate        SE        z           p        LL        UL
#  0.3664407 0.1163593 3.149216 0.001637091 0.1383806 0.5945008