HW 3 Solution

HW 3 Solution - STAT 350 Assignment 3 Solutions (75 points)...

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STAT 350 Assignment 3 Solutions (75 points) 45. (5) The normal quantiles are easy to generate using SAS. The quantile plot for this data is shown below. The pattern is obviously nonlinear, so a normal distribution is implausible for this data. The apparent break that appears in the data in the right side of the graph is indicative of data that contains outliers. 1. (a) (2) 17 0 Doesn’t have to be exact! 17 23 17 445 17 67 17 18 0000011 18 2222 18 445 18 6 18 8 (1) The distribution is reasonably symmetric in appearance and somewhat bell-shaped. The variation in the data is fairly small since the range of the values (188-170 = 18) is fairly small compared to the typical value of 180. (2) 0 889 Doesn’t have to be exact! 1 0000 1 3 1 4444 1 66 1 8889 2 11 2 2 5 2 6 2 3 00 (1) For the 'ratio' data, a typical value is around 1.6 and the distribution appears positively skewed. The hundredths digit has been truncated in the display. The variation in the data is large since the range of the data (3.08 - .84 = 2.24) is very large compared to the typical value of 1.6. The two largest values could be outliers and should be checked using the methods of Section 2.3. (b) (1) The efficiency ratio is not uniquely determined by temperature since there are several instances in the data of equal temperatures associated with different efficiency ratios. For example, the five observations with temperatures of 180 each have different efficiency ratios. 2 1 0 -1 -2 75 65 55 45 35 Normal quantile Modulus of elasticity

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(c) (3) A scatter plot of the data appears below. The points exhibit quite a bit of variation and do not appear to fall close to any straight line or simple curve. Saying linear is ok also. 2. (2 each plot) (2) With this data the relationship between the age of the lawn mower and its NO x emissions seems somewhat dubious. One might have expected to see that as the age of the lawn mower increased the emissions would also increase. We certainly do not see such a pattern. Age does not seem to be a particularly useful predictor of NO x emission. 4.
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This note was uploaded on 09/21/2011 for the course STAT 350 taught by Professor Staff during the Spring '08 term at Purdue.

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HW 3 Solution - STAT 350 Assignment 3 Solutions (75 points)...

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