Title:
Beyond Line Charts: Graphing market trends with R

Author:
Aaron Ping - Procter & Gamble, Japan K.K.

Abstract: Shampoos and Conditioners are a highly competitive market in
Japan.  Five major corporations: Procter & Gamble, Shiseido, Unilever,
Kao, and Kanebo compete for the attention of Japanese consumers.
ACNeilsen tracks market share for the more than 10,000 SKUs (Stock
Keeping Units) of Hair-Care products sold through retail channels.  In
addition, ACNeilsen provides retail measures such as pricing,
display-share, and distribution-share.  Keeping abreast of changes to
their own Hair-Care brands and competing ones is a core task of brand
managers.  Line charts and indexes are the most commonly used methods
for understanding brand growth and decline.

Although many R charts were originally designed for other analysis
purposes, they can be adapted to highlight market trends.  Tressel
plots and mosaic plots can show trends without the clutter of many
lines in one chart.  Double-histograms can highlight 'before'
vs. 'after' when the market has undergone a major change.  Vector
plots can show more than one dimension of change at a time.  Using
such charts, brand managers can make decisions from a broader visual
understanding of their markets than line-based trend charts can
provide.

Fig. 1: Market Overview Snapshot using a Mosaic plot.  Each bar
represents a major brand with each of the four partitions representing
one of the major package forms: Bottles with a lid, Pump-style
bottles, disposable Refill packages, and after-conditioner Treatments.
The width of each bar is proportional to the market share held by the
brand and the size of each partition is proportional to the percentage
of brand share coming from each package-type.  Color reflects the
share growth of each brand based on a 3-month rolling index.