Heat maps are a popular way to display varying values in a two-dimensional display. The heat map may be an actual geographic map with regions colored differently according to some variable, for example, population density or electoral results. I showed such maps, also called cartograms or choropleths, in Redrawn Electoral Maps and An Undistorted Election [...]

Some time ago I wrote about Surface and Contour Charts in Microsoft Excel in Dian Chapman’s TechTrax Ezine. In that article I outlined the data requirements for surface and contour charts, and described some of the formatting idiosyncrasies of these charts. That article was valid for Excel versions 97 through 2003, but like so many [...]

In Pareto lines on bar charts – an Excel fudge, Alex Kerin of Data Driven Consulting took data from a very badly distorted pie chart, and generated a Pareto chart. I busted the pie in Extra Distortion in a Pie Chart, but thought I’d chime in on the subject of Pareto Charts.
A Pareto Chart is [...]

Here’s a quick quiz for all of you aspiring chart experts:
Question
In the chart below, rank the following in decreasing order of value:

Red wedge
Orange wedge
Pink wedge
Sum of four smaller wedges

The real answer may surprise you (or maybe not).

Chandoo says we can Group Smaller Slices in Pie Charts to Improve Readability. Such a pie has too many labels to fit into a tight space, so you need to move the labels around and use leader lines to link the labels to their data points.

An extreme example? Judging from what I see around the [...]

Has anybody not seen this unique pie chart? This famous graphic is  purported to compare Sarah Palin’s favorability to that of Mitt Romney and Mike Huckabee. I have seen it dozens of times already, but I think the first place I saw it was in Fox’s Fuzzy Math: 193 Percent Of The Public Support Palin, [...]

This post was inspired by Moving a Pie Slice, a recent post on Patricia the Excel Diva’s Chatting about Excel blog. Patricia presents a few helpful Excel tips each week.
In Moving a Pie Slice, Patricia shows how to explode one pie segment out of the pie chart. I’ll review the protocol, not because I want [...]

In In what order to display data series?, Jan Schultink of Slides That Stick suggested changing series order to make your point clearer. In Jan’s example, he had three series in a stacked column chart.

The upper two series in the stack are almost constant from year to year, while the bottom series is increasing steadily. [...]

Elsewhere in this blog I’ve showed how to Plot Two Time Series With Different Dates:

In Category Axis Tricks for Line and Area Charts – 1 I extended this technique to show how to format parts of a line chart in distinct colors:

A reader asked how to show two years of data on two separate lines [...]

I’ve written several tutorials about creating box and whisker charts, including Horizontal Box Plots and Vertical Box Plots. I’ve also created a professional Box Plot Utility that generates box and whisker charts from raw observations. These techniques are complicated, since they are built using bar or column charts, with extra sets of series to accommodate [...]