Refer to the Engineering Structures and Technologies (Sep. 2012) study on the use of processed straw as
Question:
Refer to the Engineering Structures and Technologies (Sep. 2012) study on the use of processed straw as thermal insulation for homes, Exercise 11.4. You used data on n = 25 straw specimens (see right column) to fit a quadratic model relating y = thermal conductivity (watts per meter- Kelvin) and x = density (kilograms per cubic meter).
a. Demonstrate that the correlation between x and x2 is high. What are potential consequences of estimating the quadratic model using x and x2?
b. Give the equation relating the coded variable u for density (x), using the coding system for observational data.
c. Demonstrate that the correlation between u and u2 is near 0.
d. Fit the model, E(y) = β0 + β1u1 + β2u2 using available statistical software. Interpret the results.
Data from Exercise 11.4
An article published in Engineering Structures and Technologies (Sep. 2012) presented the results of a study on the use of processed straw as thermal insulation for homes. Chopped straw specimens were prepared and tested for thermal conductivity at a temperature of 10º Celcius. Two variables were measured for each of 25 straw specimens: y = thermal conductivity (watts per meter-Kelvin) and x = density (kilograms per cubic meter).
Step by Step Answer:
Statistics For Engineering And The Sciences
ISBN: 9781498728850
6th Edition
Authors: William M. Mendenhall, Terry L. Sincich