ordAveEffPlot: Plot Average Effects of Variables in Proportional Odds...

In davidaarmstrong/damisc: Dave Armstrong's Miscellaneous Functions

Plot Average Effects of Variables in Proportional Odds Logistic Regression

Description

For objects of class polr the function plots the average effect of a single variable holding all other variables at their observed values.

Usage

ordAveEffPlot(
  obj,
  varname,
  data,
  R = 1500,
  nvals = 25,
  plot = TRUE,
  returnInd = FALSE,
  returnMprob = FALSE,
  ...
)

Arguments

obj	An object of class polr
varname	A string providing the name of the variable for which you want the plot to be drawn.
data	Data used to estimate obj.
R	Number of simulations to generate confidence intervals.
nvals	Number of evaluation points of the function
plot	Logical indicating whether or not the result should be plotted (if TRUE) or returned to the console (if FALSE).
returnInd	Logical indicating whether average individual probabilities should be returned.
returnMprob	Logical indicating whether marginal probabilities, averaged over individuals, should be returned.
...	Arguments passed down to the call to xyplot

Details

Following the advice of Hanmer and Kalkan (2013) the function calculates the average effect of a variable holding all other variables at observed values and then plots the result.

Value

Either a plot or a list with a data frame containing the variables

mean	The average effect (i.e., predicted probability)
lower	The lower 95% confidence bound
upper	The upper 95% confidence bound
y	The values of the dependent variable being predicted
x	The values of the independent variable being manipulated

and the elements Ind or Mprob, as requested.

Author(s)

Dave Armstrong

References

Hanmer, M.J. and K.O. Kalkan. 2013. ‘Behind the Curve: Clarifying the Best Approach to Calculating Predicted Probabilities and Marginal Effects from Limited Dependent Variable Models’. American Journal of Political Science. 57(1): 263-277.

Examples

library(MASS)
data(france)
polr.mod <- polr(vote ~ age + male + retnat + lrself, data=france)
## Not run: ordAveEffPlot(polr.mod, "lrself", data=france)	

davidaarmstrong/damisc documentation built on Oct. 1, 2023, 3:05 p.m.