Minitab was used to fit the model to the data locate the

Question

RNA analysis of wheat genes. Engineers from the Department of Crop and Soil Sciences at Washington State University used regression to estimate the number of copies of a gene transcript in an aliquot of RNA extracted from a wheat plant (Electronic Journal of Biotechnology, April 15, 2004). The proportion (x1) of RNA extracted from a cold-exposed wheat plant was varied, and the transcript copy number (y, in thousands) was measured for each of two cloned genes: Mn Superoxide Dismutose (MnSOD) and Phospholipose D (PLD). The data are listed in the accompanying table. Letting x₁ = RNA proportion and x₂ = {1 if MnSOD, 0 if PLD), consider the second-order model for number of copies (y):

E(y) = β₀ + β₁x₁ + β₂x₁² + β₃x₂ + β₄x₁x₂ + β₅x₁²x₂

(a) MINITAB was used to fit the model to the data. Locate the least squares prediction equation for y on the printout shown below.

(b) Is the overall model statistically useful for predicting transcript copy number (y)? Test using α = .01.

(c) Based on the MINITAB results, is there evidence to indicate that transcript copy number (y) is curvilinearly related to proportion of RNA (x₁)? Explain.