我有Likert类型数据,一些4点量表和其他3点量表。例如:
variable.x <- c(5,2,4,5,3,1)
variable.y <- c(0,1,1,0,2,1)
my.data <- cbind(variable.x, variable.y)
library(psych)
polychoric(my.data)
#Call: polychoric(x = my.data)
#Polychoric correlations
# vrbl.x vrbl.y
#variable.x 1.00
#variable.y -0.25 1.00
# with tau of
# 0 1 2 3 4
#variable.x -0.97 -0.43 0 0.43 Inf
#variable.y -0.43 0.97 Inf Inf Inf
如何获得-0.25?
的相关性的显着性值奇怪的是,使用polycor
包会产生完全不同的结果:
library(polycor)
polychor(variable.x, variable.y, ML=TRUE, std.err=TRUE)
#Polychoric Correlation, ML est. = -0.7599 (0.2588)
#Test of bivariate normality: Chisquare = 9.088, df = 7, p = 0.2464
# Row Thresholds
# Threshold Std.Err.
#1 -0.9388 0.5519
#2 -0.5774 0.5040
#3 -0.1906 0.5267
#4 0.3979 0.5690
# Column Thresholds
# Threshold Std.Err.
#1 -0.3891 0.5683
#2 0.9692 0.5568
现在相关系数现在是-0.76,而不是-0.25。再次,我怎么能找到它的意义呢?