README

CoDaImpact provides additional tools for the interpretation of regression CoDa models. It is conceived as an extension of the compositions package.

Installation

# install.packages("devtools")
devtools::install_github("LukeCe/CoDaImpact")

Example of a Y-compositional model

Below, we estimate a CoDa model that explains the market shares of five segments of the car market in France. To illustrate the influence of the HOUSEHOLD_EXPENDITURE on the market shares in each segment we use a VariationScenario(). In this scenario the HOUSEHOLD_EXPENDITURE is moved along a grid while all other variables are fixed to the values of the first observation.

library("CoDaImpact")
data("car_market")

model_car_segements <- lmCoDa(
  ilr(cbind(SEG_A, SEG_B, SEG_C, SEG_D, SEG_E)) ~
    GDP + HOUSEHOLD_EXPENDITURE + GAS_PRICE,
  data = car_market)

VS <- VariationScenario(
  model_car_segements,
  Xvar = "HOUSEHOLD_EXPENDITURE",
  obs = 1,
  inc_size = 100, 
  n_steps = 150,
  add_opposite = TRUE)


plot(x = VS$HOUSEHOLD_EXPENDITURE, y = VS$Y[,1],type = "l", col = "red",
     main = "Variation scenario of household expenditure",
     xlab = "Household expenditure", ylab = "Market share by segment")
lines(x = VS$HOUSEHOLD_EXPENDITURE, y = VS$Y[,2],type = "l", col = "blue" )
lines(x = VS$HOUSEHOLD_EXPENDITURE, y = VS$Y[,3],type = "l", col = "green")
lines(x = VS$HOUSEHOLD_EXPENDITURE, y = VS$Y[,4],type = "l", col = "orange")
lines(x = VS$HOUSEHOLD_EXPENDITURE, y = VS$Y[,5],type = "l", col = "black")
legend("topleft",
       legend = paste0("Segment ", LETTERS[1:5]),
       col = c("red", "blue", "green", "orange", "black"),
       lty = 1)