« October 30, 2005 - November 5, 2005 | Main | November 13, 2005 - November 19, 2005 »

On the popularity of bar charts

I and others have commented, to no apparent avail, on the inadequacy of the bar chart, or its variant, such as the paired/grouped bar chart.

These two examples appeared on the same day in the Wall Street Journal.  The junkchart versions, using line charts, are clearly superior in drawing attention to the key messages.

Redocolumns2_1In the first example, the improved chart facilitates comparison on either the time axis or the type of media.

In the second example (below), all of the key messages came out more potently, including the reversal of growth directions, the cross-over circa 2001-2, the dip in early-stage investments in 1999 and leveling off of early-stage investments in recent years.


One other trend remains buried in both versions, that is, the total proportion of VC funds invested in seed, early and late stage companies increased from about 55% to 70% of the total in these 10 years.  One wonders what other investment type suffered during this period...

Reference: "TV On-Demand May Make Ads More Targeted" and "Venture-Capitalists Think Large", Wall Street Journal, Nov 9 2005.

Dizzying dots

One of Tufte's many contributions is the concept of "data-ink ratio": how much of the ink used to print a chart is used to show the data as opposed to, say, decoration?

This example, showing the quintile ranking of utility funds, has a very low data-ink ratio.  The dots serve only one purpose, to make the reader dizzy.  The data stands out once the dots are banished, as shown below. 

Reference: "Lipper Leaders", Wall Street Journal (free this week), Nov 7 2005.

Uh um

An analysis of "uh" "um" linguistic data is cited at Prof. Gelman's blog.  I highly recommend it.  My comments are at his site (tried to do a Trackback but didn't succeed).

Polling and the obvious

I noticed a creative but flawed attempt to improve upon the stacked bar chart.  In the usual stacked bar presentation, it is easy to compare the leftmost and rightmost categories, but not the middle categories.   For example (below left), try comparing the percentage who thought women's legal rights were the same against the percentage who thought family rights were the same.

Above right, one designer's solution is to disaggregate the bars (blue, gray, red), turning them into columns of squares.  ImmigrationkeyDisaggregating the bars is a good idea but the use of squares is unfortunate, especially when the relative percentage is made proportional to the edge length, not the area of the square.  Observe that one can fit four "50%" squares into the "100%" square.

I'd welcome any ideas that would improve upon the stacked bar/column chart.  How to make the middle categories easier to compare?

The poll itself raises more questions than it answers:

  • Biased sample: Asking immigrants to compare conditions between the U.S. and other countries is like asking someone who just paid $2 million for a one-bedroom apartment in Manhattan whether there is a housing bubble.  This group made a conscious decision to come to the U.S., possibly to escape what they consider unsatisfactory circumstances in their places of birth.  It makes me wonder why we need this poll since the answers are rather obvious.
  • Heterogeneity: Immigrants come in all stripes and their answers to these questions will most likely be affected by where they came from, what socio-economic status they occupy in their home countries, what level of education they have, where they live in the U.S., their family income and so on.  The aggregate numbers do not mean much when the underlying population is so diverse.
  • It would be instructive to compare these results with polls where they ask foreigners to rate their perception of America. 

Two results were omitted from the graph for unknown reasons: 34% thought the U.S. was better on "safety from crime" and 28% thought the U.S. was better on "moral values of society".

Reference: "Migrant Worry", New York Times Magazine, Nov 6, 2005.