Table 5.

Multiple regression analysis with interaction term (adjusted R² = 0.523).

Source	Type III Sum of Squares	df	Mean Square	F	p
Corrected model	150.366a	3	50.122	26.212	0.000
Intercept	23.866	1	23.866	12.481	0.001
Age	12.427	1	12.427	6.499	0.013
DPD	1.676	1	1.676	0.876	0.353
Age × DPD	0.054	1	0.054	0.028	0.867
Error	126.203	66	1.912
Total	1420.617	70
Corrected total	276.570	69

df, degree of freedom; F, the ratio of mean square for each factor to that of the error; DPD, difference in pupillary diameter. Age significantly correlated with the amplitude of accommodation, and the age variables were independent of each other.