# HW_06 - STAT 425 Fall 2016 Homework 6(Posted on Nov 6 Due...

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STAT 425 — Fall 2016 Homework 6 (Posted on Nov 6; Due Friday, Nov 18) Please submit your assignment on paper , following the Guidelines for Homework posted at the course website. (Even if correct, answers might not receive credit if they are too difficult to read.) Remember to include relevant computer output. 1. Data on the butterfat content of milk from Canadian cows of five different breeds and two different ages can be found in the butterfat dataset. (a) Determine whether there is an interaction between breed and age. (b) Determine whether there are statistically significant differences between the breeds and between the ages. (c) Present regression diagnostics for your chosen model and comment whether the assumptions have been met. (d) Is the best breed in terms of butterfat content clearly superior to the second best breed? 2. An experiment was conducted at The Ohio State University to determine the effect of using helium to fill a football (American) on the distance the football could be kicked. Two footballs were prepared: one helium-filled, and the other air-filled (but otherwise identical). On a windless day, each football was kicked a total of 39 times, and the distance traveled (yards) was recorded for each kick. The kicks were conducted in pairs (called Trials) with