Statistics Linear Regression Excel 2007

OK, so the weather has been so nice lately...

Let's see, how about for you statisticians or wannabe stat kinda guys or gals...you all remember r (linear correlation coefficient) or r2 (coefficient of determination) from statistics? Anyway, something about how well points fit a line. If r or r2 = 1, there is a perfect fit of the data to a line. In plain english, r is equal to the cross product of the sum of difference of each data point from it mean for x and y values divided by the number of data point minus 1 times the product of the standard deviation of the x and y values. Of course the line equation is y = mx + b (m is slope of the line and b is the y intercept).

In Excel after you have created a line chart (really could be several other types but makes most sense with a line chart (remember linear regression...). In Excel 2007 select the chart and the Chart Tools Layout Tab, the Analysis Command Group has Trendline, More Trendline Options (at the bottom of the list). By default, what we want in this case anyway, is Linear. This will add the best fit linear trendline to the chart. But now, maybe the best part...At the bottom of the trendline options dialog box are the options to force a Y intercept value (many times 0) and show the line equation and r2 values on the chart..pretty cool. I just think of all of the calculations to do this...

Otherwise, not into stats...never mind...

Have fun in the meantime until nextime, Joel