Sneak peek: Regression lines in XtraCharts v2009 vol 2 (ASP.NET / WinForms)

30 May 2009

One of a series of posts on the new functionality that'll appear in DXperience v2009 vol 2. This is all pre-beta stuff, we're probably something like a month from beta.

In this post, we'll look at the new regression line support that coming up in the next major release of XtraCharts.

If you do any kind of statistical analysis of some data, you would at some point plot the data on a chart and try and determine whether the data suggests some kind of simple function between the variables of the data (in general, there are one or more independent variables, and a single dependent variable whose values depend on the values of the other variables).

The simplest function to look for is a line. You plot the data points such that the X-axis is the independent variable and the Y-axis represents the dependant variable, and if the points are roughly collinear, odds are that there is a linear relationship between the variables (that is, the variables are related by an equation y = a + bx, for some a and b).

Regressionline in XtraCharts 

Linear regression analysis involves determining the underlying equation through a method called least squares. With this method, we minimize the error terms (if you like, how far away each data point is from the underlying linear function) by minimizing the sum of the squares of the errors. (The squaring of the terms removes the problem of dealing with negative error terms.) To calculate the equation of the line using the least squares method is relatively simple; indeed many calculators provide such a function.

XtraCharts now provides this linear regression and will plot the line on a point chart, as shown. You can also determine the equation of the line.

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