qiz 2

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1. A law firm wants to determine the trend in its annual billings so that it can better forecast revenues. It plots the data on its billings for the past 10 years and finds that the scatter plot appears to be linear. What formula should they use to determine the trend line?

		σ = ∑√(x - μ)2 ÷ N
		F = s12 ÷ s22
		t = (x̄ - μx-bar) ÷ s/√n
		Tt = b0 + b1t

3 points

QUESTION 2

1. A set of subjects, usually randomly sampled, selected to participate in a research study is called:

		Population
		Sample
		Mode group
		Partial selection

3 points

QUESTION 3

1. If a researcher accepts a null hypothesis when that hypothesis is actually true, she has committed:

		a type I error
		a type II error
		no error
		a causation

3 points

QUESTION 4

1. A binomial probability distribution is a discrete distribution (i.e., the x-variable is discrete).

True

False

3 points

QUESTION 5

1. The tdistribution is wider and flatter (i.e., has more variation) than the normal distribution.

True

False

3 points

QUESTION 6

1. A physician wants to estimate the average amount of time that patients spend in his waiting room. He asks his receptionist to record the waiting times for 28 of his patients and finds that the sample mean (x̄) is 37 minutes and the sample standard deviation (s) is 12 minutes. What formula would you use to construct the 95% confidence interval for the population mean of waiting times?

		t = (x̄ - μx-bar) ÷ s/√n
		µ = ∑ x ÷ N
		x̄ - t(s ÷ √n) < µ < x̄ + t(s ÷ √n)
		z = (x - µ) ÷ σ

3 points

QUESTION 7

1. When the alternative hypothesis states that the difference between two groups can only be in one direction, we call this a:

		One-tailed test
		Bi-directional test
		Two-tailed test
		Non-parametric test

3 points

QUESTION 8

1. For any probability distribution, the probability of any x-value occurring within any given range is equal to the area under the distribution and above that range.

True

False

3 points

QUESTION 9

1. The formula for ____________ is (Row total X Column total)/T

		Observed frequencies
		Degrees of freedom
		Expected frequencies
		Sampling error

3 points

QUESTION 10

1. State Senator Hanna Rowe has ordered an investigation of the large number of boating accidents that have occurred in the state in recent summers. Acting on her instructions, her aide, Geoff Spencer, has randomly selected 9 summer months within the last few years and has compiled data on the number of boating accidents that occurred during each of these months. The mean number of boating accidents to occur in these 9 months was 31 (x̄), and the standard deviation (s) in this sample was 9 boating accidents per month. Geoff was told to construct a 90% confidence interval for the true mean number of boating accidents per month. What formula should Geoff use?

		x̄ - t(s ÷ √n) < µ < x̄ + t(s ÷ √n)
		F = s12 ÷ s22
		z = (x - µ) ÷ σ
		x̄ - z(σ ÷ √n) < µ < x̄ + z(σ ÷ √n)

3 points

QUESTION 11

1. One critical difference between the assumptions for using Chi-square and the assumptions for using ANOVA is that the:

		Dependent variable for Chi-square must be measured at an interval level and for ANOVA it must be ratio
		Independent variable for Chi-square can only have up to 3 categories but for the ANOVA it can have more than 3 categories
		Dependent variable for Chi-square must be measured at a nominal or ordinal level and for ANOVA it must be interval or ratio
		None of the above

3 points

QUESTION 12

1. If the null hypothesis states that µ ≥ $50 lbs., then the test is two-tailed.

True

False

3 points

QUESTION 13

1. A researcher wants to determine if socioeconomic status (low, moderate, high) is related to smoking (yes or no). The Chi-Square null hypothesis for this study is that socioeconomic status is related to smoking behavior.

True

False

3 points

QUESTION 14

1. If a specific acupuncture technique is known to be successful in relieving headaches 80% of the time, what formula would you use to determine the probability that the technique will be successful for 4 of the next 5 patients?

		P (x out of n) = [n! ÷ x!(n – x)!] [px] [(1 – p)n-x]
		x̄w = ∑ wx ÷ ∑ w
		P(A) = (# examples of A) ÷ (total # outcomes possible)
		σ = ∑√(x - μ)2 ÷ N

3 points

QUESTION 15

1. Parametric tests can be used when the dependent variable is at any level of measurement (i.e., nominal, ordinal, interval, or ratio).

True

False

3 points

QUESTION 16

1. A requirement for using Chi-square is that the dependent variable must be measured at a nominal or ordinal level:

True

False

3 points

QUESTION 17

1. Realtor Elaine Snyderman took a random sample of 12 homes in a prestigious suburb of Chicago and found the average appraised market value (x̄) to be $780,000, and the standard deviation (s) was $49,000. What formula would you use to test the hypothesis that for all homes in the area, the mean appraised value is less than $825,000? (a = 0.05)

		z = (x - µ) ÷ σ
		t = (x̄ - μx-bar) ÷ s/√n
		z = (x̄ - μx-bar) ÷ σ/√n
		x̄ - t(s ÷ √n) < µ < x̄ + t(s ÷ √n)

3 points

QUESTION 18

1. In a time series analysis, you can use the trend equation to make a prediction for any specific time period.

True

False

3 points

QUESTION 19

1. The Willow Company manufactures automobile batteries. The company has determined that the lives of its batteries are normally distributed with a mean life (µ) of 63 months with a population standard deviation (σ) of 3 months. If someone purchases one of their batteries, what formula should they use to determine the probability that it will last less than 57 months?

		ŷ = b0 + b1x
		z = (x - µ) ÷ σ
		x̄ - z(σ ÷ √n) < µ < x̄ + z(σ ÷ √n)
		t = (x̄ - μx-bar) ÷ s/√n

3 points

QUESTION 20

1. Marketing researchers hypothesized that customer age group would affect sales of a new technology. The null hypothesis could be described as:

		Customer age group is related to sales of new technology.
		Customer age group would not affect sales of a new technology.
		Customer age group would affect sales of a new technology.
		Some factor other than age group affects sales of new technology.

3 points

QUESTION 21

1. Chi-square tests can be conducted for a 4X3 contingency table.

True

False

3 points

QUESTION 22

1. In a two-tailed t-test (hypothesis test) where alpha = .01, s = 1.7, and n = 20, the critical values for t are:

		+/- 2.09
		+/- 2.86
		+/- 2.53
		+/- 1.73

3 points

QUESTION 23

1. The area of a sampling distribution beyond which the null hypothesis is rejected is known as the:

		Sampling region
		Directional hypothesis
		Critical region
		Degrees of freedom

3 points

QUESTION 24

1. In calculating a binomial probability we are determining the number of successes out of the total number of trials in an experiment.

True

False

3 points

QUESTION 25

1. The generic formula for the estimating line used in linear regression analysis is: Y’ = b0 + b1X

True

False

3 points

QUESTION 26

1. In Bigville, a fast-food chain feels it is gaining a bad reputation because it takes too long to serve the customers. Because the chain has four restaurants in this town, it is concerned with whether all four restaurants have the same average service time. One of the owners of the fast-food chain has decided to visit each of the stores and monitor the service time for five randomly selected customers. At his four noon-time visits, he records the following service times in minutes. Do all the restaurants have the same mean service time? (Use a = 0.05)

Restaurant 1

5.5

3.5

Restaurant 2

3.5

4.5

5.5

Restaurant 3

3.5

6.5

Restaurant 4

5.5

2.5

Path: p

Words:0

9 points

QUESTION 27

American Theaters knows that a certain hit movie ran an average (μ) of 84 days in each city, and the corresponding standard deviation (σ) was 10 days. The manager of the southeastern district was interested in comparing the movie’s popularity in his region with that in all of American’s other theaters. He randomly chose 75 theaters in his region and found that they ran the movie an average (x̄) of 81.5 days. At the 0.01 significance level, can the manager conclude that there was a significant difference in the length of the picture’s run between theaters in the southeastern district and all of American’s other theaters?

Path: p

Words:0

8 points

QUESTION 28

1. The editor-in-chief of a major metropolitan newspaper has been trying to convince the paper’s owner to improve the working conditions in the pressroom. He is convinced that the noise level when the presses are running creates unhealthy levels of tension and anxiety. He recently had a psychologist conduct a test during which press operators were placed in rooms with varying levels of noise and then given a test to measure mood and anxiety levels. The following table shows the index of their degree of arousal or nervousness and the level of noise to which they were exposed (1.0 is low and 10.0 is high):

Noise Level	4	3	1	2	6	7	2	3
Degree of Arousal	39	38	16	18	41	45	25	38

1. Develop an equation relating noise level and degree of arousal. [10 POINTS]

2. Predict the degree of arousal that might be expected if the noise level is 3. [5 POINTS]