Last week in Series Lines: Useful or Chart Junk?, I wrote about Excel’s “Series Lines” feature, and how it seems like a good way to clarify the data in a stacked column chart, until you implement it and realize it just adds chart junk to your chart. I proposed a panel chart to show the stacked [...]

In Getting value on Y axis by putting X axis value on the Mr Excel forum, someone wanted to know how to find in-between values of a function, given some known data points. The approach, of course, is to interpolate values given the known points on either side of the value you need. Interpolation requires some [...]

A reader of my post about Trendline Fitting Errors asked how to calculate area under a fitted curve. His stated problem was that when he tried to calculate points based on the fit, it didn’t come close to matching his measured data, even though the fit had a very high R² value. I suspect this [...]

A very common task you may have is to take a chart you’ve painstakingly formatted and use it with new data. I described a few ways to handle this in Make a Copied Chart Link to New Data. Most commonly you have a worksheet with a bunch of data and a corresponding chart, and you [...]

In Get a Maximum and Minimum Value from Certain Charts, John Mansfield showed a simple routine he uses to find the maximum and minimum Y values in a chart. In the ensuing discussion, alternatives were suggested with various justifications. I wanted to say that this one was faster than that one, but I realized that [...]

Linear Regression People are familiar with a standard linear regression (LR) method that makes assumptions about the X and Y variables in the analysis. Excel’s built-in regression methods make these same assumptions. The X variable, also called the independent variable, is assumed to be known precisely, and all error in the regression is assumed to [...]