STA 4210 – Homework #1 – Due Sept. 17, 2014
1) Using the Grade Point Average data, complete problems 1.19, 1.23, 2.4 (95%CI, and level of significance
.05), 2.13 (Xh=30 in all parts), 2.23 (=0.05). Use R for all parts of analysis (construct the confidence
and prediction intervals directly, based on the formulas). Hand in NEATLY written answers,
computer output and program).
2) Using the Airfreight Breakage data, complete a table that gives all relevant sums of squares and
crossproducts, fitted values, and residuals. Give 95% Confidence Intervals for 0,1. Give a 95% prediction
interval for a new outcome when X=0. Give the ANOVA table and conduct the F-test to determine whether
the mean number of broken ampules is linearly related to the number transfers (=0.05). Do all parts by
hand, showing all work.
Part 3
A researcher is interested in the effect of different levels of a nutrient in the feed of mice on
weight gain. She samples 30 mice of a particular breed and assigns them randomly to one of 6
levels of the nutrient (0, 20, 40, 60, 80, 100). There are 5 mice per level. The datasets are
micegrow.xls and micegrow.dat. The response (dependent) variable is weight change over a
3-week period.
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Obtain a scatterplot of weight change versus nutrient level
Fit a simple linear regression, relating weight change to nutrient level
Test whether there is a positive association between weight change and nutrient level
Give a 95% confidence interval for the mean change in weight as nutrient level is increased
by 1 unit
 Obtain the analysis of variance table and coefficients of correlation and determination