Analysis and Visualization Likert Items
An approach to analyzing Likert response items, with an emphasis on visualizations.
The stacked bar plot is the preferred method for presenting Likert results. Tabular results
are also implemented along with density plots to assist researchers in determining whether
Likert responses can be used quantitatively instead of qualitatively. See the likert(),
summary.likert(), and plot.likert() functions to get started.
- Fixed a bug where stacked bars were in the wrong order in grouped plots.
- Plotting options are now passed as a list. The likert.options returns the default set of plotting options.
- Fixed a bug where the neutral labels would be printed twice when there were an odd number of levels and plot.percents = TRUE.
- Fixed a bug where the results for a grouped analysis with missing levels may not be correct in the print function.
- Update for ggplot2 version 2.0
- Removed all use of the reshape package.
- Fixes issue 40 where the histogram bars may not match the likert bars.
- Fix to work with the latest version of the xtable package.
- Added ability to group items by factor.
- Converted all uses of reshape to reshape2.
- Other fixes to pass R CMD CHECK.
- Added colors parameter to plot.likert.bar to define custom colors for levels.
- Fixed bug where an unused factor level would not appear in the legend.
- Added initial support for conducting gap analysis. A demo, GapAnalysis has
also been added.
- Removed dependency on a non-exported function in ggplot2.
- Can now create a likert object with a pre-summarized data frame.
- New Shiny app to demonstrate many of the features in the likert package. The
shinyLikert() function will start the app.
- Fixed bug where text.color parameter was not being used.
- Fixed bug 16.
- Fixed bug where automatic conversion to factors would not work if there were
missing levels in an item.
- Added text labels to the histogram (if include.histogram=TRUE) for the n.
- Fixed a bug where plot.likert(..., include.histogram=TRUE) would not work with a group and only one item (i.e. one column).
- Updates for newer version of R and Roxygen.
Released September 25, 2013.
- New density plot type plot(l, type='density').
- xtable function to create LaTeX and HTML tables.
- Added several parameters related to centering bar plots. Can now include the
center level and split across zero, or specify which level, or between which
levels, centering occurs.
- Plot a histogram of responses (n) alongside the barplot.
- Summary function now includes neutral column. Values will be NA if no level
is the center.
- If there is a neutral category in the bar plot it will be labeled with its
- Added parameter to wrap text in plots for long item names.
- Changed the default colors.
- Added parameter to change legend title.
- Can now plot bar plot panels horizontally.
- Changed the center=TRUE as the default for bar plots to.
- Added panel.flip to flip the placement of grouping elements and items.
- Added legend.position parameter.
- Added panel.strip.color to change the background color for panel labels.
- Added group.order to reorder how groups are plotted. This also works for items in
- Added parameters to turn off percent labels for low, high, and netural separately.
- Added a check to ensure all factors have the same number of levels.
- Items (i.e columns) that are not a factor will be converted to a factor using as.factor.
- Added reverse.levels function to reverse code factors. Useful when you wish to plot
bars in reverse order (left-to-right).
- Two new demos, RecodeFactors and UnusedLevels show how to deal with common data
issues before using the likert function.
- Added plot.percents parameter to label each category.
- Other bug fixes.