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SCM 200 Final Exam Practice Questions

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Quiz sobre SCM 200 Final Exam Practice Questions, criado por mursham22 em 16-12-2014.
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Quiz por mursham22, atualizado more than 1 year ago
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Criado por mursham22 quase 10 anos atrás
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Resumo de Recurso

Questão 1

Questão
We should determine our objectives of a study before we collect the data.
Responda
  • True
  • False

Questão 2

Questão
The numbers on a basketball jersey are an example of qualitative data.
Responda
  • True
  • False

Questão 3

Questão
A cumulative relative frequency totals to
Responda
  • 0%
  • 100%
  • The total number in your sample (n)
  • Cannot be determined without seeing the data

Questão 4

Questão
A data set that is skewed left (negative) has most of the data values on the left with a few data values trailing off to the right.
Responda
  • True
  • False

Questão 5

Questão
A descriptive measure of a sample is a parameter.
Responda
  • True
  • False

Questão 6

Questão
A stem and leaf plot is useful because it
Responda
  • shows the distribution of the data
  • contains all the original data values
  • shows the distribution of the data AND contains all the original data values
  • it is a cumulative distribution

Questão 7

Questão
The first quartile of a distribution can never be less than zero.
Responda
  • True
  • False

Questão 8

Questão
A boxplot is a good way to show the mean of a data set.
Responda
  • True
  • False

Questão 9

Questão
Generally speaking, a stem and leaf plot cannot be constructed from a boxplot, but a boxplot can be constructed from a stem and leaf plot.
Responda
  • True
  • False

Questão 10

Questão
A population consists of the numbers 3, 8, 4. The mean and median, respectively, are:
Responda
  • 5,8
  • 3,8
  • 4,5
  • 5,4

Questão 11

Questão
The median and mode are not affected by outlier values.
Responda
  • True
  • False

Questão 12

Questão
Every data set has a mode.
Responda
  • True
  • False

Questão 13

Questão
One section of SCM 200 has 20 students, another has 25 students, and a third section has 55 students. A weighted average of the number of students in these sections is:
Responda
  • 25
  • 40.5
  • 33-1/3
  • 30

Questão 14

Questão
The following measures of variation measure distance from the mean:
Responda
  • mean absolute deviation
  • variance
  • interquartile range
  • mean absolute deviation AND variance

Questão 15

Questão
Median is a measure of variability of a data set.
Responda
  • True
  • False

Questão 16

Questão
Range is sensitive to all data values.
Responda
  • True
  • False

Questão 17

Questão
If we want the average of all the deviations from the mean of a data set, we can simply add the deviations and divide by n.
Responda
  • True
  • False

Questão 18

Questão
The mean absolute deviation of the four numbers 6, 14, 14, 14 is equal to
Responda
  • 0
  • 1
  • 2
  • 3

Questão 19

Questão
The units of a population mean absolute deviation for a problem in which the units are feet are
Responda
  • feet squared
  • the absolute value of feet
  • feet
  • no units. MAD is a relative measure

Questão 20

Questão
A population has three values: 3, 7, 5. Find the population variance.
Responda
  • 0
  • 2.67
  • 1.63
  • 4
  • 2

Questão 21

Questão
A population consisted of the values 3, 7, 11, 11, 13. The population standard deviation is equal to:
Responda
  • 12.8
  • 3.58
  • 16
  • 4

Questão 22

Questão
A sample consisting of the numbers 3, 6, 9 has a sample variance equal to 12.
Responda
  • True
  • False

Questão 23

Questão
The number of hours a child spent watching TV over the past three days was 15, 3, 9. Compute the sample standard deviation.
Responda
  • 24
  • 6
  • 3
  • 2

Questão 24

Questão
A standard deviation can sometimes be larger in numerical value than a variance.
Responda
  • True
  • False

Questão 25

Questão
The coefficient of variation computed from the three sample values 25, 30, 35 would be equal to 20.
Responda
  • True
  • False

Questão 26

Questão
95% of data values that conform to a bellshaped distribution lie within how many standard deviations of the mean?
Responda
  • 0
  • 1
  • 2
  • 3

Questão 27

Questão
Student score = 70 Class mean = 80 Standard deviation = 5 The standard score is equal to 2.
Responda
  • True
  • False

Questão 28

Questão
Drawing an ace of spades and a three of hearts are complementary events.
Responda
  • True
  • False

Questão 29

Questão
The items in a sample space must be
Responda
  • complementary
  • exhaustive
  • random
  • complementary AND exhaustive

Questão 30

Questão
When a probability is described in terms of the proportion of times that and event can be theoretically expected to occur, it is an example of relative frequency probability.
Responda
  • True
  • False

Questão 31

Questão
A couple plans to have 3 children. Assuming male-female births are equally likely, what is the probability that couple will have at least one girl among the three children?
Responda
  • 1/3
  • 2/3
  • 3/8
  • 7/8

Questão 32

Questão
When one throws a die 1,000 times and determines that the probability of obtaining a six on a die is one-sixth, that person has used the theoretical approach to probability.
Responda
  • True
  • False

Questão 33

Questão
A student has three pairs of socks in her closet: one black pair, one red pair, and one white pair. If she randomly selects two socks from her closet, what is the probability that they will be the same color? (i.e. They will be a matching pair.)
Responda
  • 2/3
  • .20
  • .80
  • .75

Questão 34

Questão
The distribution of people’s heights is an example of a discrete probability distribution.
Responda
  • True
  • False

Questão 35

Questão
The sum of the probabilities in a discrete probability distribution could total 1.2.
Responda
  • True
  • False

Questão 36

Questão
Probabilities associated with random variables must all be equal.
Responda
  • True
  • False

Questão 37

Questão
A quiz with 10 questions on it was given to a class of 10 students. Each question was worth one point and the results are summarized below: X = number of correct answers = 10, 9, 8, 7, 6, 5 or less, with frequencies f(X) = 3, 2, 1, 2, 2, 0 respectively. The quiz score mean (expected value) is:
Responda
  • 8
  • 8.2
  • 9
  • 7.8

Questão 38

Questão
Find the variance of X for the following probability distribution: X P(X) 1 .4 3 .2 5 .4
Responda
  • 1.6
  • 4
  • 8/3
  • 3.2

Questão 39

Questão
Find the standard deviation of X for the following probability distribution: X P(X) 20 .50 30 .10 60 .40
Responda
  • 4.29
  • 18.4
  • 19
  • 361

Questão 40

Questão
Non-random samples involve unequal probabilities.
Responda
  • True
  • False

Questão 41

Questão
For a random variable X to have a binomial distribution, it is necessary that:
Responda
  • X represents the number of successes
  • the outcome of each trial is a success
  • the n trials are statistically dependent on eachother
  • X represents the number of successes AND the outcome of each trial is a success

Questão 42

Questão
A success in a binomial distribution indicates that something positive has occurred.
Responda
  • True
  • False

Questão 43

Questão
A weighted die is thrown. Success is defined as getting an even number. The probability of success is .55. The probability of getting 2 even numbers when throwing the die four times is approximately .3675.
Responda
  • True
  • False

Questão 44

Questão
Samantha calls on 10 houses per day selling Girl Scout cookies. Historically, 3 out of 4 customers buy cookies. Assuming the binomial distribution applies here, the variance of this distribution is:
Responda
  • 1.875
  • 1.37
  • 7.5
  • 2.5

Questão 45

Questão
The standard deviation of the distribution in the previous problem is 1.37.
Responda
  • True
  • False

Questão 46

Questão
The standard normal distribution has a mean of 1 and a standard deviation of 0.
Responda
  • True
  • False

Questão 47

Questão
If X is a normal random variable with a mean of 10 and a standard deviation of 1/2, then X = 14 is 8 standard deviations away from the mean.
Responda
  • True
  • False

Questão 48

Questão
Use the standard normal curve to determine the probability that the random variable z will fall between –0.04 and 0.44. That is, find the following probability: P(–0.04 < z < 0.44):
Responda
  • .4000
  • .4800
  • .1860
  • .1540

Questão 49

Questão
In the standard normal z-distribution, the probability between z = –1 and z = +1 is the same as the probability between z = –0.5 and z = +1.5.
Responda
  • True
  • False

Questão 50

Questão
The lifetime of tires is normally distributed with a mean of 50,000 miles and a standard deviation of 3,000 miles. The warranty is for 46,000 miles. What proportion of the tires will fail after the warranty but before 52,000 miles? Indicate the interval below that contains this probability.
Responda
  • .0000 to .2000
  • .2001 to .4000
  • .6001 to .8000
  • .8001 to 1.000
  • .4001 to .6000

Questão 51

Questão
When 6.3% of the data values fall below a normally distributed random variable, the correct z-value is -1.53.
Responda
  • True
  • False

Questão 52

Questão
Weights of cereal boxes are normally distributed with a mean of 15 oz. and a standard deviation of .5 oz. What is the minimum weight a box could be and remain in the top 14.46% of all boxes filled?
Responda
  • 16.10 oz.
  • 14.47 oz.
  • 15.53 oz.
  • The answer cannot be determined with the information given

Questão 53

Questão
An unbiased estimator is:
Responda
  • no more likely to be above the population parameter than below.
  • always better than a biased estimator.
  • is a specific observed value of a statistic.
  • always better than a biased estimator AND is a specific observed value of a statistic.

Questão 54

Questão
The sample range is generally an unbiased estimator of the population range.
Responda
  • True
  • False

Questão 55

Questão
A disadvantage of a point estimate is that we don’t know how accurate that estimate is.
Responda
  • True
  • False

Questão 56

Questão
A sampling distribution is a distribution of all possible values of a statistic for a given sample size.
Responda
  • True
  • False

Questão 57

Questão
All standard deviations are standard errors, but not all standard errors are standard deviations.
Responda
  • True
  • False

Questão 58

Questão
If a random sample of size 16 is taken from a skewed population whose mean is equal to 360 and standard deviation is 36, the standard error of the mean would equal:
Responda
  • 9
  • 90
  • 10
  • 1/9

Questão 59

Questão
Given a population standard deviation, as sample size increases, standard error also increases.
Responda
  • True
  • False

Questão 60

Questão
For a test, the pop. mean score is 1100 and the pop. st. dev. is 100. If the test is given to 36 randomly selected individuals, what is the probability that the sample mean will lie between 1090 and 1122? After finding the appropriate probability, indicate the interval that includes this probability:
Responda
  • .0000 to .3000
  • .8501 to 1.000
  • .6001 to .7000
  • .3001 to .6000
  • .7001 to .8500

Questão 61

Questão
The Central Limit Theorem assures us that the sampling distribution for the sample mean approaches a normal distribution as the sample size increases, regardless of the shape of the population distribution.
Responda
  • True
  • False

Questão 62

Questão
Records have shown that 15% of patients are not satisfied with their care. A poll of 100 patients was conducted. What is the probability that more than 18 patients will not be satisfied with their care? After finding the probability, indicate the interval that includes this probability.
Responda
  • .0000 to .3000
  • .8501 to 1.000
  • .6001 to .7000
  • .3001 to .6000
  • .7001 to .8500

Questão 63

Questão
Confidence intervals specify parameter values in advance.
Responda
  • True
  • False

Questão 64

Questão
In using the standard normal distribution to establish a confidence interval for the average number of hours that a light bulb will last, what is the appropriate z-value to use for a 34% level of confidence:
Responda
  • 0.17
  • 0.1331
  • 0.44
  • 0.99

Questão 65

Questão
Other things being equal, a 90% confidence interval is wider than a 95% confidence interval.
Responda
  • True
  • False

Questão 66

Questão
A bank wants to determine mean waiting time. It samples 100 customers and the mean time is 6.9 minutes. Population standard deviation is assumed to be 4 minutes. Find a 91.98% confidence interval of mean waiting time:
Responda
  • 6.9 +/- 0.7
  • 6.9 +/- 0.92
  • 6.9 +/- 0.5
  • 6.9 +/- 1.75

Questão 67

Questão
A t-distribution with 5 degrees of freedom has less area in the tails than a standard normal distribution.
Responda
  • True
  • False

Questão 68

Questão
The following is true about the t-distribution:
Responda
  • like the standard normal distribution, there is only one t-distribution
  • the mean is 0
  • is determined by the parameter mu
  • approaches the standard normal as degrees of freedom become smaller

Questão 69

Questão
The important distinction between the z-statistic and t-statistic is that z is used for large sample sizes and t is used for small sample sizes.
Responda
  • True
  • False

Questão 70

Questão
A confidence interval for a true population mean is to be constructed from sample data with size n = 23. The t-value to use for setting a 90% level of confidence is:
Responda
  • 1.321
  • 1.319
  • 1.717
  • 1.714
  • 1.645

Questão 71

Questão
A random sample of 4 glass rods is tested and reveals the following breaking strength in pounds: 8, 4, 2, 6. Construct an 80% confidence interval for the true mean breaking strength:
Responda
  • (1.73, 8.27)
  • (3.74, 6.26)
  • (-.46, 10.46)
  • (2.89, 7.11)

Questão 72

Questão
Increasing the sample size, but using the same level of confidence, produces a confidence interval that has a greater likelihood of containing the parameter being estimated.
Responda
  • True
  • False

Questão 73

Questão
The mean age of viewers of TV shows interests advertisers. A major network believes that the mean age of viewers of a show is more than 30. Many affiliate stations claim the mean age is not greater than 30. What is H0 for testing the major network’s claim. Population mean mu is:
Responda
  • less than 30
  • greater than 30
  • not equal to 30
  • at least 30
  • at most 30

Questão 74

Questão
In testing the hypothesis below, a statistician found that z = -0.44. What is the p-value? H0: mu = 10 Ha: mu does not equal 10
Responda
  • .67
  • .66
  • .56
  • .33
  • .17

Questão 75

Questão
In order to compute the p-value from sample data, we need to know both the alternative hypothesis and the level of significance.
Responda
  • True
  • False

Questão 76

Questão
To test that the mean lifetime of light bulbs is at least 900 hours (pop. normally distributed and pop. st. dev. is 20), a random sample of 25 bulbs is tested, yielding a sample mean of 894 hours. Find the p-value for the test. Indicate which interval below contains the p-value.
Responda
  • .0301 to .1000
  • .5001 to 1.000
  • .2001 to .5000
  • .0000 to .0300
  • .1001 to .2000

Questão 77

Questão
If the p-value for a given hypothesis testing problem is .055 and the level of significance is .05, the null hypothesis should be rejected.
Responda
  • True
  • False

Questão 78

Questão
In the following hypothesis test, H0: mu = 4 Ha: mu > 4 the t-value was computed to be –2 and degrees of freedom are 11. The correct p-value is .025 < p-value < .05.
Responda
  • True
  • False

Questão 79

Questão
Given an upper-tailed t-test for one mean with 30 degrees of freedom and the value of the test statistic computed from the sample data t = 2.75 would yield a p-value equal to .01.
Responda
  • True
  • False

Questão 80

Questão
Four runners were randomly sampled and it was found they ran 23, 19, 23, and 23 miles per week. If we wish to test the claim that the population mean running distance is less than 25 miles per week, what conclusion should be reached at the 1% level of significance?
Responda
  • Reject the claim by rejecting Ho
  • Accept the claim by rejecting Ho
  • Reject the claim by accepting Ho
  • Accept the claim by accepting Ho

Questão 81

Questão
In statistical process control, if the pvalue is less than or equal to alpha, we should conclude the process is under control.
Responda
  • True
  • False

Questão 82

Questão
If mu = 40 pounds, sigma = 4 pounds, and sample size is 36, the LCL and UCL on a control chart for x would be:
Responda
  • 38 pounds, 42 pounds
  • 28 pounds, 52 pounds
  • 38.67 pounds, 41.33 pounds
  • 35 pounds, 45 pounds

Questão 83

Questão
A poll in a senatorial contest revealed that 40 out of 400 randomly selected people indicated a preference for candidate A. Find a 95.44% confidence interval for the proportion of voters who favor candidate A.
Responda
  • .07 to .13
  • .06 to .14
  • .05 to .15
  • .09 to .11
  • .38 to .42

Questão 84

Questão
A promoter is deciding whether to book a new band. The promoter decides to do a survey to try to estimate the true proportion of individuals in the area who will attend the concert. What should sample size be to estimate the proportion to within 5% with a 68.26% confidence level? (Assume maximum error possible.)
Responda
  • 25
  • 100
  • 400
  • 200

Questão 85

Questão
In selecting a sample size to estimate a population proportion, the sample size will depend, among other things, upon the level of confidence that is to be used for the estimate.
Responda
  • True
  • False

Questão 86

Questão
A company is planning to test whether the market share of a new product during its first year on the market is more than 20 percent. The appropriate null hypothesis would be that the market share percentage is
Responda
  • greater than 20%
  • less than or equal to 20%
  • less than 20%
  • not equal to 20%
  • greater than or equal to 20%

Questão 87

Questão
A manufacturer claims that no more than 20% of all units will experience a failure within the first 5 years. 100 purchasers randomly selected were asked to report failures. If 28 failures were reported, what conclusion should be reached about the manufacturer’s claim? alpha = 5%.
Responda
  • Accept the claim by rejecting Ho
  • Reject the claim by rejecting Ho
  • Accept the claim by accepting Ho
  • Reject the claim by accepting Ho

Questão 88

Questão
Assume for a given hypothesis testing problem, the test statistic was computed and led to a rejection of the null at alpha of .01. Based on this information, we can further conclude that since H0 was rejected at the 1% level, then H0
Responda
  • Must be rejected at alpha of 10%
  • must be accepted at alpha of 10%
  • must be accepted at alpha of 5%
  • must be accepted at alpha of 5% and 10%

Questão 89

Questão
The t-test for n1 = 15 and n2 = 15 using paired testing has
Responda
  • 14 degrees of freedom
  • 13 degrees of freedom
  • 29 degrees of freedom
  • 28 degrees of freedom
  • 30 degrees of freedom

Questão 90

Questão
A paired difference experiment produced the following data: n = 30, xbar1 = 72, xbar2 = 75.5, Dbar = -3.5, and SD squared = 17. SE(Dbar) is equal to:
Responda
  • -0.64
  • 0.64
  • 0.75
  • -0.75
  • 3.10

Questão 91

Questão
Assume a matched pairs test for a mean difference with a two-tailed alternative hypothesis and the number of paired differences n = 4. If the computed test statistic t = 2.353, then the p-value would be equal to .05.
Responda
  • True
  • False

Questão 92

Questão
An analyst is testing a new system to see if it uses a different processing time than the old system. The time for each in seconds was recorded for 28 samples. Old System: mean = 21.2, s = 3.2, n = 28 New System: mean = 24.3, s = 2.1, n = 28 Difference (Old – New): mean = – 3.1, s = 1.4, n = 28 What is the appropriate statistical test?
Responda
  • Paired t-test for mean differences
  • Hypothesis test for one proportion
  • regression analysis
  • Independent t-test for mean differences

Questão 93

Questão
An analyst is testing a new system to see if it uses a different processing time than the old system. The time for each in seconds was recorded for 28 samples. Old System: mean = 21.2, s = 3.2, n = 28 New System: mean = 24.3, s = 2.1, n = 28 Difference (Old – New): mean = – 3.1, s = 1.4, n = 28 What is the alternative hypothesis for the question above?
Responda
  • Ha: muD = 0
  • Ha: MuD < 0
  • Ha: MuD > 0
  • Ha: MuD does not equal 0

Questão 94

Questão
In a simple linear regression analysis, the p-value associated with a test of the slope coefficient was equal to .026, which would lead us to conclude that a linear relationship exists between the two variables at the 5% level of significance.
Responda
  • True
  • False

Questão 95

Questão
An analyst is testing a new system to see if it uses a different processing time than the old system. The time for each in seconds was recorded for 28 samples. Old System: mean = 21.2, s = 3.2, n = 28 New System: mean = 24.3, s = 2.1, n = 28 Difference (Old – New): mean = – 3.1, s = 1.4, n = 28 The correct t-value for the previous question is:
Responda
  • 62
  • 11.72
  • -62
  • -11.72

Questão 96

Questão
An analyst is testing a new system to see if it uses a different processing time than the old system. The time for each in seconds was recorded for 28 samples. Old System: mean = 21.2, s = 3.2, n = 28 New System: mean = 24.3, s = 2.1, n = 28 Difference (Old – New): mean = – 3.1, s = 1.4, n = 28 If the p-value for this test is less than .002 and alpha is .05, analysts would conclude that
Responda
  • the old system uses more processing time
  • the old system uses less processing time
  • the systems use the same processing time
  • the system processing times are unequal

Questão 97

Questão
A doctor claims the average person is more than 11 pounds overweight. To test the claim, the difference between actual and ideal weight of 36 randomly selected people was calculated. The sample mean and sample standard deviation were 14 and 5 pounds respectively. At alpha of 1%, can we conclude the claim is true?
Responda
  • Yes, the claim is true by rejecting Ho
  • Yes, the claim is true by accepting Ho
  • No, the claim is not true by rejecting Ho
  • No, the claim is not true by accepting Ho

Questão 98

Questão
The difference between the independent sample and paired sample approach is that with the independent sample approach, a background variable's effect is controlled by pairing.
Responda
  • True
  • False

Questão 99

Questão
In general, the paired samples method is preferred over the independent samples method.
Responda
  • True
  • False

Questão 100

Questão
The t-test for n1 = 15 and n2 = 7 using the independent samples approach has (assuming equal population variances)
Responda
  • 14 degrees of freedom
  • 6 degrees of freedom
  • 21 degrees of freedom
  • 20 degrees of freedom
  • 22 degrees of freedom

Questão 101

Questão
Given the following information about a hypothesis test of the difference between two means based on independent random samples. (Assume normal distributions with equal variances.) The correct pvalue is between .005 and .01. H0: μ1 – μ2 = 0 Ha: μ1 – μ2 ≠ 0 x1 = 16.32, x2 = 17.44, s1squared = 4.3, s2squared = 2.2, n1 = 30, n2 = 32
Responda
  • True
  • False

Questão 102

Questão
The best statistic for pi1 - pi2 is p1 – p2.
Responda
  • True
  • False

Questão 103

Questão
For n1 = 70 and n2 = 100 from populations 1 and 2, the number of successes are 35 and 35 respectively. The estimate of the difference between pi1 - pi2 is
Responda
  • 0.35
  • 0.15
  • 0.70
  • 0.50
  • 0.42

Questão 104

Questão
For n1 = 200 and n2 = 100 from populations 1 and 2, the numbers of successes are 35 and 25 respectively. The value of the pooled sample proportion p-hat is 0.20.
Responda
  • True
  • False

Questão 105

Questão
In an upper-tailed test of the difference of two proportions, the z-value was calculated to be 2.69. The p-value for this test would then be .0036.
Responda
  • True
  • False

Questão 106

Questão
The purpose of a scatterplot is to visually determine if a relationship exists between two variables.
Responda
  • True
  • False

Questão 107

Questão
In using the regression model for forecasting the next value (or an individual value) of y, the prediction interval will be
Responda
  • the same as the estimating interval
  • narrower than the estimating interval
  • wider than the estimating interval
  • wider or narrower, depending on the data

Questão 108

Questão
The coefficient of determination (R2) is equal to 0.64, and the linear regression equation which indicates an inverse relationship between x and y is equal to ŷ = 2 - .74x, then the correlation coefficient must necessarily be equal to:
Responda
  • -.80
  • +.64
  • -.74
  • either -.80 or +.80

Questão 109

Questão
In a simple linear regression and correlation problem, a correlation coefficient of .80 means that 64% of the variation in y can be explained by x.
Responda
  • True
  • False

Questão 110

Questão
When R2 = 1, then Se = Sy.
Responda
  • True
  • False

Questão 111

Questão
A correlation coefficient of –1.0 would imply that the standard error of the estimate Se would necessarily be equal to 0.
Responda
  • True
  • False

Questão 112

Questão
Standard error is measured in the units of the x variable.
Responda
  • True
  • False

Questão 113

Questão
The range of a regression coefficient is – 1 to + 1.
Responda
  • True
  • False

Questão 114

Questão
Standard deviation of height = 2.45 inches. Standard deviation of weight = 23 pounds. Correlation = .56 If we are predicting weight from height, the regression coefficient is 5.26.
Responda
  • True
  • False

Questão 115

Questão
If ŷ = 15 + 10x, then the estimated value of y when x = 5 is:
Responda
  • 25
  • 65
  • 10
  • 15
  • 55

Questão 116

Questão
When H0 is accepted in a regression model, we conclude:
Responda
  • A linear relationship exists between x and y.
  • The x variable is statistically significant.
  • The x variable is not statistically significant.
  • A linear relationship exists between x and y AND the x variable is statistically significant.

Questão 117

Questão
Seasonality can be incorporated into regression models with dummy variables.
Responda
  • True
  • False

Questão 118

Questão
For the linear equation ŷ = 50 – 2x where y is the number of items sold and x is the price of the product in $, which is true?
Responda
  • The equation represents an inverse relationship between y and x.
  • The equation represents a positive relationship between y and x because the constant term 50 is greater than 0.
  • The slope of the line is – 2 dollars per each item sold.
  • The slope of the line is +50 dollars per each item sold.

Questão 119

Questão
If a correlation exists between y and x, then necessarily either y causes x or x causes y.
Responda
  • True
  • False

Questão 120

Questão
The advantage of multiple regression over simple regression is that we can change more than one variable at a time.
Responda
  • True
  • False

Questão 121

Questão
If ŷ = 31 + 1.2x1 – 3.4x2 + 5x3, then the estimated value of y when x1 = – 6, x2 = 3, and x3 = 2 is:
Responda
  • 31.7
  • 25.4
  • 23.6
  • 38

Questão 122

Questão
The alternative hypothesis in a multiple regression problem is that no linear relationship exists between a given independent variable and y.
Responda
  • True
  • False

Questão 123

Questão
The correlation coefficient between college GPA and H.S. GPA is .70. The correlation coefficient between college GPA and H.S. rank is .60. Which of the following is true?
Responda
  • 70% of the variation in college GPA can be explained by H.S. GPA.
  • 60% of the variation in college GPA can be explained by H.S. GPA.
  • H.S. GPA is a better predictor of college GPA than H.S. rank.
  • There is an inverse relationship between H.S. GPA and College GPA.

Questão 124

Questão
Adding another variable to a regression equation will make R2
Responda
  • decrease
  • increase
  • stay the same or increase
  • stay the same or decrease
  • increase, decrease, or stay the same

Questão 125

Questão
The purpose of R2 adjusted is to discern the effect of adding a variable to a model.
Responda
  • True
  • False

Questão 126

Questão
Adding another variable to a regression equation will necessarily make R2 adjusted increase.
Responda
  • True
  • False

Questão 127

Questão
It is possible for a variable to be significant in multiple regression when that same variable is not significant in simple regression.
Responda
  • True
  • False

Questão 128

Questão
Stable environments are critical for effective time series analysis.
Responda
  • True
  • False

Questão 129

Questão
Which of the following is not a component of time series?
Responda
  • Seasonality
  • Cycle
  • Randomness
  • Trend
  • Contingency

Questão 130

Questão
The regression model based on annual data for the last 20 years is ŷ = 20.35 + 2.4x. The actual value of y when x = 12 is 52. The value of the forecasting error is:
Responda
  • 68.35
  • 16.35
  • 2.85
  • 49.15
  • 40

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