Tuesday
February 9, 2016

# Homework Help: Precalculus / Statistics

Posted by Ryan St. Laurent on Thursday, May 24, 2007 at 7:34pm.

I have a question about residual plots and regression equations.

The data is:

X Y
1 6.1
2 5.5
3 9.8
4 10.6
5 14.2
6 21.5
7 29.9
8 37.2
9 50.6
10 64
11 77.6

What function fits this data the best, between Exponential, Linear, Quadratic, and Power.
Also how do you make residual plots on a TI-83 Graphing Calculator?

First, graph it out. what does the graph look like. not straight so toss out Linear. Constantly rising (no humps), so (probably) toss out quadratic. Could be a power function, but offhand id say it was an exponential function (in that the function seems to be growing by e^(ax))

So, next take the natural log of your y values, and graph that. I get something resembling a straight line. Estimate an OLS regression on the logged values. Plot the predicted from the regression, and actual values; the difference between the two are the residuals (which could easily be plotted).