A polynomial equation follows the simple rule that additional powers of x terms are added. Note that if you have N-1 terms in a polynomial equation, you can get a perfect regression fit. Keep in mind that not all data meets the basic x,y pair requirement for using regression analysis.
Some spreadsheets can fit linear equations to data using a variety of methods.
In Lotus, Quattro Pro and Excel, regression can be run manually via menu commands. In Excel, you can also fit regression lines and equations using the x-y scatter graph type. In some of the latest versions of all these spreadsheets, there are ways to calculate least squares regression using built-in functions, which have the advantage of recalculating immediately whenever data are changed. Print the graph and the statistics for the regression analysis. Other tools are helpful for saving time in comparing the fit of different equations to a given data set.