Fluorocarbon plasmas are used in the production of semiconductor materials. In the Journal of Applied Physics (Dec. 1, 2000), electrical engineers at Nagoya University (Japan) studied the kinetics of fluorocarbon plasmas in order to optimize material processing. In one portion of the study, the surface production rate of fluorocarbon radicals emitted from the production process was measured at various points in time (in milliseconds) after the radio frequency power was turned off.

Rate Time

1.00 ............0.1

0.80 ............0.3

0.40 ...........0.5

0.20 ...........0.7

0.05 ...........0.9

0.00 ...........1.1

–0.05............1.3

–0.02............1.5

0.00 ........... 1.7

–0.10 ........... 1.9

0.15 ...........2.1

–0.05 ........... 2.3

–0.13 ........... 2.5

–0.08 ........... 2.7

0.00 ...........2.9

The data are given in the table above and saved in the RADICALS file. Consider a model relating surface production rate (y) to time (x).

a. Graph the data in a scatterplot. What trend do you observe?

b. Fit a quadratic model to the data. Give the least squares prediction equation.

c. Is there sufficient evidence of upward curvature in the relationship between surface production rate and time after turnoff? Use α = .05.