STAT200 week 8 homework

Week 8 Homework

10. If an experiment is conducted with 5 conditions and 6 subjects in each

condition, what are dfn and dfe?

17. The following data are from a hypothetical study on the effects of age and time on scores on a test of reading comprehension. Compute the analysis of variance summary table.

Treatment Effects of a Drug on Cognitive Functioning in Children with Mental Retardation and ADHD for questions 28 and 29


Overview

This study investigated the cognitive effects of stimulant medication in children with mental retardation and Attention-Deficit/Hyperactivity Disorder. This case study shows the data for the Delay of Gratification (DOG) task. Children were given various dosages of a drug, methylphenidate (MPH) and then completed this task as part of a larger battery of tests. The order of doses was counterbalancedso that each dose appeared equally often in each position. For example, six children received the lowest dose first, six received it second, etc. The children were on each dose one week before testing.

This task, adapted from the preschool delay task of the Gordon Diagnostic System (Gordon, 1983), measures the ability to suppress or delay impulsive behavioral responses. Children were told that a star would appear on the computer screen if they waited “long enough” to press a response key. If a child responded sooner in less than four seconds after their previous response, they did not earn a star, and the 4-second counter restarted. The DOG differentiates children with and without ADHD of normal intelligence (e.g., Mayes et al., 2001), and is sensitive to MPH treatment in these children (Hall & Kataria, 1992).

Questions to Answer
Does higher dosage lead to higher cognitive performance (measured by the number of correct responses to the DOG task)?

Design Issues
This is a repeated-measures design because each participant performed the task after each dosage.

Descriptions of Variables

Variable	Description
d0	Number of correct responses after taking a placebo
d15	Number of correct responses after taking .15 mg/kg of the drug
d30	Number of correct responses after taking .30 mg/kg of the drug
d60	Number of correct responses after taking .60 mg/kg of the drug

28. (AT) The dataset ADHD Treatment has four scores per subject. a. Is the design between-subjects or within-subjects? b. Create an ANOVA summary table.

29. (AT) Using the Anger Expression Index from the Angry Moods study as the dependent variable, perform a 2x2 ANOVA with gender and sports

participation as the two factors. Do athletes and non-athletes differ significantly in how much anger they express? Do the genders differ significantly in Anger Expression Index? Is the effect of sports participation significantly different for the two genders?

Use the following information to answer the next three exercises.Suppose a group is interested in determining whether teenagers obtain their drivers licenses at approximately the same average age across the country. Suppose that the following data are randomly collected from five teenagers in each region of the country. The numbers represent the age at which teenagers obtained their drivers licenses.

	Northeast	South	West	Central	East
	16.3	16.9	16.4	16.2	17.1
	16.1	16.5	16.5	16.6	17.2
	16.4	16.4	16.6	16.5	16.6
	16.5	16.2	16.1	16.4	16.8
? =	________	________	________	________	________
S2 =	________	________	________	________	________

H0:?1 =?2 =?3 =?4 =?5

H?: At least any two of the group means?1,?2, …,?5 are not equal.

61.degrees of freedom – numerator:df(num) = _________

63.F statistic = ________

69.A researcher wants to know if the mean times (in minutes) that people watch their favorite news station are the same.

CNN	FOX	LOCAL
45	15	72
12	43	37
18	68	56
38	50	60
23	31	51
35	22

Suppose thatTable 13.24shows the results of a study.

Assume that all distributions are normal, the four population standard deviations are approximately the same, and the data were collected independently and randomly. Use a level of significance of 0.05.

71.Are the mean number of times a month a person eats out the same for whites, blacks, Hispanics and Asians? Suppose thatTable 13.26shows the results of a study.

WHITE	BLACK	HISPANIC	ASIAN
6	4	7	8
8	1	3	3
2	5	5	5
4	2	4	1
6		6	7

Assume that all distributions are normal, the four population standard deviations are approximately the same, and the data were collected independently and randomly. Use a level of significance of 0.05.

77.A grassroots group opposed to a proposed increase in the gas tax claimed that the increase would hurt working-class people the most, since they commute the farthest to work. Suppose that the group randomly surveyed 24 individuals and asked them their daily one-way commuting mileage. The results are as follows.

WORKING CLASS	PROFESSIONAL (MIDDLE INCOME)	PROFESSIONAL (WEALTHY)
17.8	16.5	8.5
26.7	17.4	6.3
49.4	22.0	4.6
9.4	7.4	12.6
65.4	9.4	11.0
47.1	2.1	28.6
19.5	6.4	15.4
51.2	13.9	9.3

Determine whether or not the variance in mileage driven is statistically the same among the working class and professional (middle income) groups. Use a 5% significance level.

81.Is the variance for the amount of money, in dollars, that shoppers spend on Saturdays at the mall the same as the variance for the amount of money that shoppers spend on Sundays at the mall? Suppose that theTable 13.34shows the results of a study.

SATURDAY	SUNDAY	SATURDAY	SUNDAY
75	44	62	137
18	58	0	82
150	61	124	39
94	19	50	127
62	99	31	141
73	60	118	73
	89