ci.slope.median.bs: Confidence interval for the slope of medians in a one-factor...

In statpsych: Statistical Methods for Psychologists

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

Description

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)

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

statpsych documentation built on June 10, 2025, 5:11 p.m.