Homework 6 - Due: Thursday, April 1st

For each of the following three problems: I) without looking at the actual data, decide on the appropriate analysis, II) check the assumptions of the model, III) perform the analysis, and IV) state your conclusions. In each problem, assume that an (approximate) experiment-wise a of 0.05 is desired.

1) The following is taken from: Glantz, A.G. and Slinker, B. K. (1990). Primer of Applied Regression and Analysis of Variance. New York: McGraw Hill.

It is based on: Montross, J.F., Neas, F., Smith, C.L., and Hensley, J.H. (1988). The effect of role-playing high gender identification on the California Psychological Inventory. Journal of Clinical Psychology, 44: 160-164.

Clinical psychologists have developed several ways to assess an individual's personality traits from answers given to a series of carefully selected questions. One such instrument is the California Psychological Inventory, which consists of 15 scales designed to give insight into some facet of a respondent's behavior and personality and 3 additional validity scales designed to detect individuals trying to fake certain personality traits. Even though these validity scales are present, Montross and his coworkers wondered if the overall assessment of personality with this instrument could be affected by faking strong gender identification - men responding in a very "macho" manner and women responding in a very "feminine" manner - without being detected by the validity scales.

To evaluate the effect of faking strong gender identification, they administered the California Psychological Inventory to 16 men and 16 women. Half of each sex were given standard instructions, whereas the other half were instructed to role-play so that they answered the questions in the way they thought an extremely masculine man (male subjects) or extremely feminine woman (female subjects) would answer. The data for 1 of the 15 personality assessment scales, the Sp scale, appears below.



		Honest Answers		Role Playing
Male		64.0			37.7
		75.6			53.5
		60.6			33.9
		69.3			78.6
		63.7			46.0
		53.3			38.7
		55.7			65.8
		70.4			68.4

Female		41.9			25.6
		55.0			23.1
		32.1			32.8
		50.1			43.5
		52.1			12.2
		56.6			35.4
		51.8			28.0
		51.7			41.9


2) The data in this problem is from: Al-Marshed, A.M. (1981). Compaction effects on asphaltic concrete durability. M.S. thesis, Civil Engineering, University of Arizona.

The tensile strength (in pounds per square inch) of various types of asphaltic concrete is being investigated. There are two aggregate types (the material it is made of) and four compaction types (how it is prepared). One of the compaction types is to just leave it static, the other three are levels of kneading. It is thought that Basalt aggregate makes a stronger concrete than the Silicious aggregate. It is thought that there may be a difference in the effect of switching from Basalt to Silicious when the compaction method is Static vs. when the compaction method is one of the Kneading methods. Finally, it is desired to determine what the most effective method is when the Regular Kneading is not an option.



			Compaction Method
				-------------------Kneading----------------
Aggregate 	Static		Regular		Low		Very Low
Type
---------------------------------------------------------------------------
Basalt		68		126		93		56
		63		128		101		59
		65		133		98		57

Silicious	71		107		63		40
		66		110		60		41
		66		116		59		44
---------------------------------------------------------------------------




3) The data in Table 9.27 (page 458) is concerned with the yield of rice at four different locations (K=Kay, E=Eagle Lake, B=Bay City, C=El Campo), using three varieties of rice (N, L, B), and four levels of nitrogen (60, 90, 120, and 150). It is desired to see which variety of rice is best in general, and which amount of nitrogen is best in general. It is also desired to see if the effect of changing the rice variety is consistent across the four locations, and if the effect of changing the nitrogen level is consistent across the four locations.


          BAY_CITY    B       B        60     3910
          BAY_CITY    B       B        90     4015
          BAY_CITY    B       B       120     3894
          BAY_CITY    B       B       150     4870
          BAY_CITY    B       L        60     2481
          BAY_CITY    B       L        90     3514
          BAY_CITY    B       L       120     3726
          BAY_CITY    B       L       150     4071
          BAY_CITY    B       N        60     3146
          BAY_CITY    B       N        90     2806
          BAY_CITY    B       N       120     3739
          BAY_CITY    B       N       150     4681
          EAGLE_LK    E       B        60     1561
          EAGLE_LK    E       B        90     3088
          EAGLE_LK    E       B       120     2869
          EAGLE_LK    E       B       150     3957
          EAGLE_LK    E       L        60     4917
          EAGLE_LK    E       L        90     5466
          EAGLE_LK    E       L       120     4672
          EAGLE_LK    E       L       150     5680
          EAGLE_LK    E       N        60     1330
          EAGLE_LK    E       N        90     2642
          EAGLE_LK    E       N       120     2252
          EAGLE_LK    E       N       150     1715
          EL_CAMPO    C       B        60     4340
          EL_CAMPO    C       B        90     4024
          EL_CAMPO    C       B       120     4306
          EL_CAMPO    C       B       150     4479
          EL_CAMPO    C       L        60     4804
          EL_CAMPO    C       L        90     4480
          EL_CAMPO    C       L       120     4619
          EL_CAMPO    C       L       150     4048
          EL_CAMPO    C       N        60     3768
          EL_CAMPO    C       N        90     4167
          EL_CAMPO    C       N       120     4212
          EL_CAMPO    C       N       150     4293
          KATY        K       B        60     6129
          KATY        K       B        90     5697
          KATY        K       B       120     6853
          KATY        K       B       150     6457
          KATY        K       L        60     5641
          KATY        K       L        90     5544
          KATY        K       L       120     6318
          KATY        K       L       150     6297
          KATY        K       N        60     4193
          KATY        K       N        90     4681
          KATY        K       N       120     4758
          KATY        K       N       150     4463