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Assignment 7

Due Thursday, April 25.

Turn in problems # 1 and 2.

Problem 1:
(From Weisberg, 1985.) The data in the file coins.dat are from a paper written by W. Stanley Jevons (1868). In a study of coinage, Jevons weighed 274 gold sovereigns that he had collected from circulation in Manchester, England. For each coin, he recorded the date of issue and the weight after cleaning to the nearest .001 gram. In the file coins.dat, the coins have been grouped into age classes coded 1 to 5, roughly corresponding to the age of the coin in decades. For each age class, the data includes the number of coins measured, their average weight, standard deviation, and minimum and maximum weight. Note that the standard weight of a gold sovereign was supposed to be 7.9876 grams; the minimum legal weight was 7.9379 grams.

Problem 2:
(From Weisberg, 1985.) The data in the file alfalfa.dat were collected to study the variation in rent paid in 1977 for agricultural land planted to alfalfa. The data include

AlfRent = average rent per acre planted to alfalfa
TilRent = average rent paid for all tillable land
CowDens = density of dairy cows (number per square mile)
Pasture = proportion of farmland used as pasture
Liming = whether liming is required to grow alfalfa

The unit of analysis is a county in Minnesota; the 67 counties with appreciable rented farmland are included.

Alfalfa is a high protein crop that is suitable feed for dairy cows. It is thought that rent for land planted to alfalfa relative to rent for other agricultural purposes would be higher in areas with a high density of dairy cows, and rents would be lower in counties where liming is required, since that would mean additional expense.

Use the techniques learned so far to explore these data with regard to understanding rent structure. What do you conclude concerning the hypotheses stated in the last paragraph?

# 10.3, 10.4, 10.7, 10.10, 11.3 (a), 11.5, 11.8, 11.9 (you may plot the log-likelihood instead of the residual sums of squares), 11.11, 11.16, 11.17, 11.18, 11.19.

next up previous
Next: About this document Up: Homework Assignments STA 6208: Previous: Assignment 6

Brett Presnell
Thu Apr 18 15:52:37 EDT 1996