Contrast coefficients for the slope of a quantitative factor

Computes the contrast coefficients that are needed to estimate the slope of a line in a one-factor design with a quantitative factor.

slope.contrast(x)

Arguments

x

vector of numeric factor levels

Value

Returns the vector of contrast coefficients

Examples

x <- c(25, 50, 75, 100)
slope.contrast(x)
#>      Coefficient
#> [1,]      -0.012
#> [2,]      -0.004
#> [3,]       0.004
#> [4,]       0.012

# Should return:
#      Coefficient
# [1,]      -0.012
# [2,]      -0.004
# [3,]       0.004
# [4,]       0.012