Chapter 7 PCA Perceptual Maps

Sources for this chapter:

• R for Marketing Research and Analytics, Second Edition (2019). Chris Chapman and Elea McDonnell Feit
  • http://r-marketing.r-forge.r-project.org/index.html

Data for this chapter:

• The greekbrands data is used from the MKT4320BGSU course package. Load the package and use the data() function to load the data.

  # Load the course package
  library(MKT4320BGSU)
  # Load the data
  data(greekbrands)

7.1 Introduction

Base R can produce basic perceptual maps from a PCA object, but cannot create a joint-space map easily. For joint-space maps, better looking perceptual maps, and to make the process easier, I have created a user defined function, which is part of the MKT4320BGSU package.

• percmap returns a ggplot created perceptual (or joint-space) map.

7.2 User Defined Function

7.2.1 Preparation

• For the user defined function, we must pass the function a data frame with the variables to be used in creating the principal components, the grouping variable (i.e., brand/product name), and if applicable, the preference variable
  • The data frame does not need to be aggregated, but must contain ONLY those variables

library(dplyr)
# For a perceptual map, store variables selected using dplyr to 'pmdata'
pmdata <- greekbrands %>% 
    select(perform, leader, fun, serious, bargain, value, brand)

# For a joint space map, store variable selected using dplyr to 'jsmdata'
jsmdata <- greekbrands %>%
    select(perform, leader, fun, serious, bargain, value, pref, brand)

7.2.2 Using the function

• The percmap user defined function can easily product a perceptual map or joint-space map based on the first two principal components
  • Requires the following packages:
    • ggplot2
    • dplyr
• Usage: percmap(data, group="", pref="") where:
  • data is the PCA variable data
  • group="" is the name of the grouping variable
  • pref="" is the name of the preference variable
    • Can be excluded if no preference variable
• Returns:
  • A perceptual map if pref is not included
  • A joint space map if pref is included
• Examples:
  • Perceptual Map

  percmap(pmdata, group="brand")

  
  • Joint Space Map

  percmap(jsmdata, group="brand", pref="pref")