I’ve written a bit about regression and curve fitting; see Regression Approach to a Simple Physics Problem, Choosing a Trendline Type, and Trendline Fitting Errors. A blog reader asked for help with some sample data that he couldn’t fit. Here is the data.

I plotted the data and gave it the hairy eyeball. Not a linear [...]

In You are NOT spider man, so why do you use radar charts? Chandoo presented a “petal chart” as an alternative to a radar chart (or spider chart, after its spider-web-like appearance). Here is the radar chart Chandoo wanted to replace:

And here is the replacement petal chart:

Several years ago I helped someone who was having trouble with a fitted trendline in an Excel chart. I saved the example, because I knew I’d have a blog someday, and I’d need a topic. I will use this example to describe a number of errors people encounter when fitting data. The errors are listed [...]

In US Employment Slump Chart I used a panel column chart to display the size of nonfarm sectors of the US workforce and the change in number of jobs in each sector. It is a panel chart even though the percent of workforce and job change panels are not separated by a line. The white [...]

In U.S. Job Market Skid Chart, Tony of Support Analytics presents a chart from Business Week. The chart shows change in employment figures in nonfarm job sectors compared to a year ago. Tony thought the use of human figures instead of solid bars was distorting and confusing. He also felt the sort order made the [...]

In Waterfall Charts, Fancy Waterfall Chart, and Waterfall Chart that Crosses the X Axis, I have described techniques for constructing waterfall charts in Excel. I have also written a Waterfall Chart utility that allows the user to construct waterfall charts charts directly from the data. The utility inserts a new worksheet, adds a table with [...]

I compared stacked and clustered charts in Stacked vs. Clustered. Stacked charts seem like they’d be good at showing proportions making up whole quantities, but I showed that the stacks only clearly display the bottom item in the stack and the total stack.
To illustrate this shortcoming, Nicolas Bissantz shows us a stacked bar chart showing [...]

I learned from Tim Mayes in Office Labs Chart Advisor for Excel that Microsoft’s Office Labs has developed an add-in that advises you based on your data what chart type you should use. From the Office Labs Chart Advisor page:
Chart Advisor is a prototype that provides an alternate approach for creating charts in Excel 2007. [...]

In Can You Improve this Graph Showing Suicide Rates in Japan?, Nathan of FlowingData shows a chart of long-term unemployment rates and suicide rates in Japan. The chart comes from Suicide Epidemic in Japan.

What’s wrong with this chart (which I’ve reproduced below)?

Axis label is faulty. “Japan and Suicide Rate” should be “Japan Long Term [...]

In yesterday’s post, Add a Target Line, I showed how to add a simple horizontal line target indicator to a chart. What if your target isn’t constant. I’m not talking about your boss’ moving target, but a case illustrated by the following dummy data. Our company makes widgets, which are more popular in spring and [...]