Seed germination study. Researchers at the University of North Carolina-Greensboro investigated a model for the rate of seed germination (Journal of Experimental Botany, January 1993). In one experiment, alfalfa seeds were placed in a specially constructed germination chamber. Eleven hours later, the seeds were examined and the change in free energy (a measure of germination rate) recorded. The results for seeds germinated at seven different temperatures are given in the table. The data were used to fit a simple linear regression model, with y = change in free energy and x = temperature.
(a) Graph the points in a scatterplot.
(b) Find the least squares prediction equation.
(c) Plot the least squares line, part b, on the scatterplot of part a.
(d) Conduct a test of model adequacy. Use α = .01.
(e) Use the plot, part c, to locate any unusual data points (outliers).
(f) Eliminate the outlier, part e, from the data set, and repeat parts a-d.