University of Maryland, College Park

STAT 200 WEEK 8 HOMEWORK

1)A team of cognitive psychologists studying the effects of sleep deprivation on short-term memory decay had eight participants stay in a sleep lab for two days. Four participants were randomly assigned to a condition in which they were not permitted to sleep during that period, while the other four participants were allowed to sleep when they wanted to. At the end of the two days, the participants completed a short-term memory task that yielded the results in the table that follows.

Mean Number of Letters Remembered

Using the .05 significance level, did sleep deprivation reduce short-term memory? Choose the correct H_O and H_A statements:

Question 1 options:

A) HO : μdeprived = μnormal HA : μdeprived < μnormal

2. HO : μdeprived = μnormal HA : μdeprived ≠ μnormal

3. HO : pdeprived = pnormal HA : pdeprived < pnormal

4. HO : μdeprived = μnormal HA : μdeprived > μnormal

Question 2

A team of cognitive psychologists studying the effects of sleep deprivation on short-term memory decay had eight participants stay in a sleep lab for two days. Four participants were randomly assigned to a condition in which they were not permitted to sleep during that period, while the other four participants were allowed to sleep when they wanted to. At the end of the two days, the participants completed a short-term memory task that yielded the results in the table that follows.

Mean Number of Letters Remembered

Using the .05 significance level, did sleep deprivation reduce short-term memory? The most appropriate hypothesis test to use for this scenario is:

Question 2 options:

A) t - test for independent means

2. t – test for dependent means

3. two-population proportion t-test

4. z – test for two population means

Question 3

A B2B Marketing Insider blog of October 7, 2010 examined five currently-used sales closing techniques. Sales scenarios are presented to a sample of 230 purchasing executives. Each subject received one of the five closing techniques or a scenario in which no sales close was achieved. After reading the sales scenario, each executive was asked to rate his/her level of trust in the salesperson on a 7-point scale. The

following table reports the six treatments employed in the study and the number of subjects receiving each treatment:

(Source: Based on Hawes, J.M. “Do Closing Techniques Diminish Prospect Trust?” from Industrial Marketing Management, September 1996, Volume 25(5))

Is the salesperson’s level of trust influenced by the choice of closing method? Test at 5% significance level.

Choose the correct H_O and H_A statements:

Question 3 options:

A) H_O : μ₁ = μ₂ = μ₃ = μ₄ = μ₅ = μ₆

H_A : At least three population means are different

B) H_O : μ₁ = μ₂ = μ₃ = μ₄ = μ₅ = μ₆

H_A : At least two population means are different

C) H_O : μ₁ = μ₂ H_A : μ₁ ≠ μ₂

D) H_O : p₁ = p₂ = p₃ = p₄ = p₅ = p₆

H_A : At least two proportions are different

Question 4

A B2B Marketing Insider blog of October 7, 2010 examined five currently-used sales closing techniques. Sales scenarios are presented to a sample of 230 purchasing executives. Each subject received one of the five closing techniques or a scenario in which no sales close was achieved. After reading the sales scenario, each executive was asked to rate his/her level of trust in the salesperson on a 7-point scale. The following table reports the six treatments employed in the study and the number of subjects receiving each treatment:

Is the salesperson’s level of trust influenced by the choice of closing method? Test at 5% significance level.

The most appropriate hypothesis test to use for this scenario is: Question 4 options:

1. Χ² test for goodness of fit

2. t - test for independent means
3. C) one-way ANOVA

4. t – test for single population mean

5. two-population proportion z-test

Question 5

An experimenter conducted a study of the relation of size in a particular species of bird to behavioral displays of dominance. The results for the first four birds observed were as follows.

Using α = 0.05, is the relation of size to behavioral display statistically significant?

Choose the correct H_O and H_A statements:

Question 5 options:

A) H_O : linear relationship is not statistically significant (population correlation coefficient = 0)

H_A : linear relationship is statistically significant (population correlation coefficient

≠ 0)

2. H_O : p₁ = p₂ H_A : p₁ ≠ p₂

3. H_O : μ₁ = μ₂ H_A : μ₁ ≠ μ₂

4. H_O : r = 0 H_A : r ≠ 0

Question 6

An experimenter conducted a study of the relation of size in a particular species of bird to behavioral displays of dominance. The results for the first four birds observed were as follows.

Using α = 0.05, is the relation of size to behavioral display statistically significant?

The most appropriate hypothesis test to use for this scenario is: Question 6 options:

1. z – test for two population proportion

2. Χ² test for independence

3. t - test for independent means

4. t - test for dependent means

E) t - test for significance of correlation coefficient r

Question 7

Each year, Kiplinger’s compiles its list of Best Value Cities. One of the statistics used in this ranking is the cost-of-living index compiled by the US Department of Labor Bureau of Labor Statistics. The index measures the cost of living in a city relative to the national average of 100. In 2011, Pueblo Colorado had the lowest index (84), while New York City had an index of 118. The following table lists the cost of living for seven Southeastern US cities:

Is the true mean cost of living index for Southeastern US cities lower than the national mean cost-of- living index of 100? Test at 2% significance level.

Choose the correct H_O and H_A statements:

Question 7 options:

1. HO : μSoutheast = μNational HA : μSoutheast ≠ μNational

2. HO : pSoutheast = pNational HA : pSoutheast ≠ pNational

C) HO : μSoutheast = μNational HA : μSoutheast <

D) HO : μSoutheast = μNational HA : μSoutheast > μNational

Question 8

Each year, Kiplinger’s compiles its list of Best Value Cities. One of the statistics used in this ranking is the cost-of-living index compiled by the US Department of Labor Bureau of Labor Statistics. The index measures the cost of living in a city relative to the national average of 100. In 2011, Pueblo Colorado had the lowest index (84), while New York City had an index of 118. The following table lists the cost of living for seven Southeastern US cities:

Is the true mean cost of living index for Southeastern US cities lower than the national mean cost-of- living index of 100? Test at 2% significance level.

The most appropriate hypothesis test to use for this scenario is:

Question 8 options:

1. z test for single population proportion

2. z – test for single sample

3. z – test for single population mean

4. t test for single population mean
5. E) t - test for single sample

Question 9

A Harris Poll conducted October 28, 2008 surveyed 2119 US adults who were asked “when you think of rising health care costs, who do you think is most responsible?” One theory is that 50% of adults blame insurance companies, 10% blame pharmaceutical companies, 10% blame Federal and state governments, 10% blame hospitals, 10% blame physicians, 5% blame some other entity, and 5% are unsure who is most responsible. Actual survey responses follow:

At a 0.02 level of significance, do the actual results match the theoretical percentages?

Choose the correct H_O and H_A statements:

Question 9 options:

A) H_O : Distribution of observed frequency percentages for healthcare blame FITS distribution of expected frequency percentages for healthcare blame

H_A : Distribution of observed frequency percentages for healthcare blame DOES NOT FIT distribution of expected frequency percentages for healthcare blame (≠)

2. H_O : Distribution of observed frequency percentages for healthcare blame DOES NOT FIT distribution of expected frequency percentages for healthcare blame (≠)

H_A : Distribution of observed frequency percentages for healthcare blame FITS distribution of expected frequency percentages for healthcare blame

3. HO : μexpected = μobserved HA : μexpected ≠ μobserved
4. D) HO : pexpected = pobserved HA : pexpected ≠ pobserved

Question 10

A Harris Poll conducted October 28, 2008 surveyed 2119 US adults who were asked “when you think of rising health care costs, who do you think is most responsible?” One theory is that 50% of adults blame insurance companies, 10% blame pharmaceutical companies, 10% blame Federal and state governments, 10% blame hospitals, 10% blame physicians, 5% blame some other entity, and 5% are unsure who is most responsible. Actual survey responses follow:

At a 0.02 level of significance, do the actual results match the theoretical percentages?

The most appropriate hypothesis test to use for this scenario is:

Question 10 options:

1. two population proportion z - test

2. Χ² test for independence

3. one-way ANOVA

4. t - test for independent means

E) Χ² test for goodness-of-fit

Question 11

The August 2008 edition of Academy of Management Journal featured an investigation of the performance and timing of corporate acquisitions. The investigation discovered that in a random sample of 2778 firms, 748 announced one or more acquisitions during the year 2000. Does the sample provide sufficient evidence to indicate that the true percentage of all firms that announced one or more acquisitions during the year 2000 is less than 30%? Test to a level of significance of 0.05.

Choose the correct H_O and H_A statements:

Question 11 options:

1. H_O : μ = 30%

H_A : μ ≠ 30%

2. H_O : μ = 30%

H_A : μ > 30%

3. H_O : μ = 30%

H_A : μ < 30%

D) H_O : p = 30%

H_A : p < 30%

Question 12

The August 2008 edition of Academy of Management Journal featured an investigation of the performance and timing of corporate acquisitions. The investigation discovered that in a random sample of 2778 firms, 748 announced one or more acquisitions during the year 2000. Does the sample provide sufficient evidence to indicate that the true percentage of all firms that announced one or more acquisitions during the year 2000 is less than 30%? Test to a level of significance of 0.05.

The most appropriate hypothesis test to use for this scenario is:

Question 12 options:

1. t - test for single population mean

2. t - test for single sample

C) z test for single population proportion

D) z - test for single population mean

E) z - test for single sample

Question 13  

In a study to test the effects of science fiction movies on people's belief in the supernatural, seven people completed a measure of belief in the supernatural before and after watching a popular science fiction movie. Participants' scores are listed below with high scores indicating higher levels of belief.

Using the .01 significance level, does participants' belief in the supernatural change after watching the movie?

Choose the correct H_O and H_A statements:

Question 13 options:

1. H_O : μ₁ = μ₂ H_A : μ₁ ≠ μ₂
2. B) H_O : μ₁ = μ₂ H_A : μ₁ > μ₂

3. H_O : μ₁ = μ₂ H_A : μ₁ < μ₂
4. D) H_O : p₁ = p₂ H_A : p₁ ≠ p₂

Question 14

In a study to test the effects of science fiction movies on people's belief in the supernatural, seven people completed a measure of belief in the supernatural before and after watching a popular science fiction movie. Participants' scores are listed below with high scores indicating higher levels of belief.