A number of investigations have focused on the problem of assessing loads that can be ma...

A number of investigations have focused on the problem of assessing loads that can be manually handled in a safe manner. The article “Anthropometric, Muscle Strength, and Spinal Mobility Characteristics as Predictors in the Rating of Acceptable Loads in Parcel Sorting” (Ergonomics [1992]: 1033–1044) proposed using a regression model to relate the dependent variable

a. What is the population regression function?

b. What are the values of the population regression coefficients?

c. Interpret the value of β₁.

d. Interpret the value of β₃.

e. What is the mean rating of acceptable load when extent of left lateral bending is 25 cm, dynamic hand grip endurance is 200 seconds, and trunk extension ratio is 10 N/kg?

f. If repeated observations on rating are made on different individuals, all of whom have the values of x₁, x₂, and x₃ specified in Part (e), in the long run approximately what percentage of ratings will be between 13.5 kg and 33.5 kg?