The article “Readability of Liquid Crystal Displays: A Response Surface” (Human Factors...

The article “Readability of Liquid Crystal Displays: A Response Surface” (Human Factors [1983]: 185–190) used a multiple regression model with four independent variables, where

y = error percentage for subjects reading a four digit liquid crystal display

x₁ = level of backlight (from 0 to 122 cd/m)

x₂ = character subtense (from .025° to 1.34°)

x₃ = viewing angle (from 0° to 60°)

x₄ = level of ambient light (from 20 to 1500 lx)

The model equation suggested in the article is

a. Assume that this is the correct equation. What is the mean value of y when x₁ = 10, x₂ = .5, x₃ = 50, and x₄ = 100?

b. What mean error percentage is associated with a backlight level of 20, character subtense of .5, viewing angle of 10, and ambient light level of 30?

c. Interpret the values of β₂ and β ₃.