How to Compare Against the Previous Period in a Stacked Column Chart

Introduction

This article describes how to go from a table like this:

To a stacked column chart which compares against the previous period:

Requirements

A table with at least two columns and at least one row.

Method

Create a table with the Nominal - Multi by date.
Set the statistics testing to compare to previous period. To do so:
- Select the table
- In the Object Inspector, click the Properties tab and from the Significance menu, select Advanced > Test Type.
- From the Date: menu, select Compare to previous period
Use R to reshape the table. There are two ways to do this:

Using the Statistical Assumptions Attitributes

Click Calculation > Custom Code right

Copy and paste the following R program into the R CODE box (you will need to change the variable names to match the ones in your file).

# Getting table. Note that this is a four dimensional array. 
x = table.Brand.attitude.by.Interview.Date.5
dims = dim(x)
n.brands = dims[1]
n.statements = dims[2]
n.periods = dims[3]
brand.names = dimnames(x)[[1]]

# Getting stat testing information. Note that this appears as a data frame.
# The stat testing is stored in a data frame, which is structured
# so that the first rows in the data frame represent the first row of the table
# (that is, it is storing the stat testing information according to the rows
# in the table that contains the percentages)
# By happy coincidence in this case it is already in the same order that we will
# want so that it matches up with them modifications that we will make to the 
# table containing the percentages

stat.testing.info =  attr(x, "QStatisticsTestingInfo")

# Rearrangin the percentages to a format that is liked by the visualization
# swapping around dimensions 
x = aperm(x, c(3, 2, 1))

# Replacing a 3D array with a 2D array, by subscripting and then splicing by row
library(abind)
x = abind(x[,,1], x[,,2], x[,,3], along = 1)

# Updating column names
rownames(x) = paste(rep(brand.names, rep(n.periods, n.brands)),
                    rownames(x)[1:n.periods])

# Appending the statistic name, so Displayr recognizes the data in the table
attr(x, "statistic") <- "Column %"

# Appending the stat testing
attr(x,  "QStatisticsTestingInfo") = stat.testing.info
x
rearranged = x

Click Calculate
From the Visualization menu, select Column > Stacked Column
Click Inputs > DATA SOURCE: > Output in Pages
Select the output from your R program:

The results are as follows:

Using the Z-Statisic and Annotations in the Visualization

Click Calculation > Custom Code right

Copy and paste the following R program into the R CODE box (you will need to change the variable names to match the ones in your file).

# Getting table. Note that this is a four dimensional array. 
x = table.Brand.attitude.by.Interview.Date.6
dims = dim(x)[1:3]# Ignoring last dimension as unneeded
n.brands = dims[1]
n.periods = dims[3]
brand.names = dimnames(x)[[1]]

# swapping around dimensions 
x = aperm(x, c(3, 2, 1, 4))

# Replacing a four dimensional array with a 3 dimensional array by 
# subscripting and then splicing together by row

library(abind)
x = abind(x[,,1, ], x[,,2, ], x[,,3, ], along = 1)

# Updating column names
n.months = dim(x)
rep(n.periods, n.brands)
rownames(x) = paste(rep(brand.names, rep(n.periods, n.brands)),
                    rownames(x)[1:n.periods])
rearranged.with.z = x