Engineers From The Department Of Crop And Soil Sciences At Washington State University In Pullman Wa Used Regression T 1 (78.74 KiB) Viewed 51 times
Engineers from the Department of Crop and Soil Sciences at Washington State University in Pullman, WA, used regression to estimate the number of copies of a gene transcript in an aliquot of ribonucleic acid (RNA) extracted from a wheat plant (see reference below). The proportion (1) 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: Manganese-dependent Superoxide Dismutase (MnSOD) and Phospholipase D (PLD). The data are stored in the WHEATRNA csv file on myCourses and partly listed below. RNA Proportion Number of Copies (y, thousands) PLD 80 0.00 0.00 83 MnSOD 401 336 : 1,272 1,256 1.00 1.00 187 199 (a) Write a first-order multiple regression model for the number of copies (y) as a function of the proportion (x) of RNA extracted and the gene type (MnSOD or PLD). Assume that proportion of RNA and gene type interact to affect y. (b) Use R to fit the model you wrote in part (a) to the data. Report the least squares prediction equation for y. (c) Conduct a test to determine whether, in fact, proportion of RNA and gene type interact. Test at level a = .01. (a) Use the results from part (b) to estimate the rate of increase of number of copies (y) with proportion (1) of RNA extracted for the MnSOD gene type. (e) Repeat part (d) for the PLD gene type. What do you conclude?
RNA MNSOD PLD 0 401 80 0 336 83 0 337 75 0.33 711 132 0.33 637 148 0.33 602 115 0.5 985 147 0.5 650 142 0.5 747 146 0.67 904 146 0.67 1007 150 0.67 1047 184 0.8 1151 173 0.8 1098 201 0.8 1061 181 1 1261 193 1 1272 187 1 1256 199
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