1798072
Pregunta 1
Pregunta
We should determine our objectives
of a study before we collect the data.
Respuesta
- True
- False
Pregunta 2
Pregunta
The numbers on a basketball jersey
are an example of qualitative data.
Respuesta
- True
- False
Pregunta 3
Pregunta
A cumulative relative frequency
totals to
Respuesta
-
0%
-
100%
-
The total number in your sample (n)
-
Cannot be determined without seeing the data
Pregunta 4
Pregunta
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.
Respuesta
- True
- False
Pregunta 5
Pregunta
A descriptive measure of a sample is
a parameter.
Respuesta
- True
- False
Pregunta 6
Pregunta
A stem and leaf plot is useful
because it
Respuesta
-
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
Pregunta 7
Pregunta
The first quartile of a distribution can
never be less than zero.
Respuesta
- True
- False
Pregunta 8
Pregunta
A boxplot is a good way to show the
mean of a data set.
Respuesta
- True
- False
Pregunta 9
Pregunta
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.
Respuesta
- True
- False
Pregunta 10
Pregunta
A population consists of the numbers 3,
8, 4. The mean and median, respectively,
are:
Respuesta
-
5,8
-
3,8
-
4,5
-
5,4
Pregunta 11
Pregunta
The median and mode are not
affected by outlier values.
Respuesta
- True
- False
Pregunta 12
Pregunta
Every data set has a mode.
Respuesta
- True
- False
Pregunta 13
Pregunta
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:
Respuesta
-
25
-
40.5
-
33-1/3
-
30
Pregunta 14
Pregunta
The following measures of variation
measure distance from the mean:
Respuesta
-
mean absolute deviation
-
variance
-
interquartile range
-
mean absolute deviation AND variance
Pregunta 15
Pregunta
Median is a measure of variability of
a data set.
Respuesta
- True
- False
Pregunta 16
Pregunta
Range is sensitive to all data values.
Respuesta
- True
- False
Pregunta 17
Pregunta
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.
Respuesta
- True
- False
Pregunta 18
Pregunta
The mean absolute deviation of the four
numbers 6, 14, 14, 14 is equal to
Respuesta
-
0
-
1
-
2
-
3
Pregunta 19
Pregunta
The units of a population mean absolute
deviation for a problem in which the units
are feet are
Respuesta
-
feet squared
-
the absolute value of feet
-
feet
-
no units. MAD is a relative measure
Pregunta 20
Pregunta
A population has three values: 3, 7, 5.
Find the population variance.
Respuesta
-
0
-
2.67
-
1.63
-
4
-
2
Pregunta 21
Pregunta
A population consisted of the values 3, 7,
11, 11, 13. The population standard
deviation is equal to:
Respuesta
-
12.8
-
3.58
-
16
-
4
Pregunta 22
Pregunta
A sample consisting of the numbers 3, 6,
9 has a sample variance equal to 12.
Respuesta
- True
- False
Pregunta 23
Pregunta
The number of hours a child spent
watching TV over the past three days
was 15, 3, 9. Compute the sample
standard deviation.
Respuesta
-
24
-
6
-
3
-
2
Pregunta 24
Pregunta
A standard deviation can sometimes be
larger in numerical value than a variance.
Respuesta
- True
- False
Pregunta 25
Pregunta
The coefficient of variation computed
from the three sample values 25, 30, 35
would be equal to 20.
Respuesta
- True
- False
Pregunta 26
Pregunta
95% of data values that conform to a bellshaped
distribution lie within how many
standard deviations of the mean?
Respuesta
-
0
-
1
-
2
-
3
Pregunta 27
Pregunta
Student score = 70
Class mean = 80
Standard deviation = 5
The standard score is equal to 2.
Respuesta
- True
- False
Pregunta 28
Pregunta
Drawing an ace of spades and a three
of hearts are complementary events.
Respuesta
- True
- False
Pregunta 29
Pregunta
The items in a sample space must be
Respuesta
-
complementary
-
exhaustive
-
random
-
complementary AND exhaustive
Pregunta 30
Pregunta
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.
Respuesta
- True
- False
Pregunta 31
Pregunta
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?
Respuesta
-
1/3
-
2/3
-
3/8
-
7/8
Pregunta 32
Pregunta
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.
Respuesta
- True
- False
Pregunta 33
Pregunta
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.)
Respuesta
-
2/3
-
.20
-
.80
-
.75
Pregunta 34
Pregunta
The distribution of people’s heights
is an example of a discrete
probability distribution.
Respuesta
- True
- False
Pregunta 35
Pregunta
The sum of the probabilities in a
discrete probability distribution could
total 1.2.
Respuesta
- True
- False
Pregunta 36
Pregunta
Probabilities associated with random
variables must all be equal.
Respuesta
- True
- False
Pregunta 37
Pregunta
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:
Respuesta
-
8
-
8.2
-
9
-
7.8
Pregunta 38
Pregunta
Find the variance of X for the following
probability distribution:
X P(X)
1 .4
3 .2
5 .4
Respuesta
-
1.6
-
4
-
8/3
-
3.2
Pregunta 39
Pregunta
Find the standard deviation of X for the
following probability distribution:
X P(X)
20 .50
30 .10
60 .40
Respuesta
-
4.29
-
18.4
-
19
-
361
Pregunta 40
Pregunta
Non-random samples involve
unequal probabilities.
Respuesta
- True
- False
Pregunta 41
Pregunta
For a random variable X to have a
binomial distribution, it is necessary that:
Respuesta
-
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
Pregunta 42
Pregunta
A success in a binomial distribution
indicates that something positive has
occurred.
Respuesta
- True
- False
Pregunta 43
Pregunta
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.
Respuesta
- True
- False
Pregunta 44
Pregunta
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:
Respuesta
-
1.875
-
1.37
-
7.5
-
2.5
Pregunta 45
Pregunta
The standard deviation of the
distribution in the previous problem
is 1.37.
Respuesta
- True
- False
Pregunta 46
Pregunta
The standard normal distribution has
a mean of 1 and a standard deviation
of 0.
Respuesta
- True
- False
Pregunta 47
Pregunta
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.
Respuesta
- True
- False
Pregunta 48
Pregunta
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):
Respuesta
-
.4000
-
.4800
-
.1860
-
.1540
Pregunta 49
Pregunta
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.
Respuesta
- True
- False
Pregunta 50
Pregunta
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.
Respuesta
-
.0000 to .2000
-
.2001 to .4000
-
.6001 to .8000
-
.8001 to 1.000
-
.4001 to .6000
Pregunta 51
Pregunta
When 6.3% of the data values fall
below a normally distributed random
variable, the correct z-value is -1.53.
Respuesta
- True
- False
Pregunta 52
Pregunta
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?
Respuesta
-
16.10 oz.
-
14.47 oz.
-
15.53 oz.
-
The answer cannot be determined with the information given
Pregunta 53
Pregunta
An unbiased estimator is:
Respuesta
-
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.
Pregunta 54
Pregunta
The sample range is generally an
unbiased estimator of the population
range.
Respuesta
- True
- False
Pregunta 55
Pregunta
A disadvantage of a point estimate is
that we don’t know how accurate that
estimate is.
Respuesta
- True
- False
Pregunta 56
Pregunta
A sampling distribution is a
distribution of all possible values of a
statistic for a given sample size.
Respuesta
- True
- False
Pregunta 57
Pregunta
All standard deviations are standard
errors, but not all standard errors are
standard deviations.
Respuesta
- True
- False
Pregunta 58
Pregunta
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:
Respuesta
-
9
-
90
-
10
-
1/9
Pregunta 59
Pregunta
Given a population standard
deviation, as sample size increases,
standard error also increases.
Respuesta
- True
- False
Pregunta 60
Pregunta
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:
Respuesta
-
.0000 to .3000
-
.8501 to 1.000
-
.6001 to .7000
-
.3001 to .6000
-
.7001 to .8500
Pregunta 61
Pregunta
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.
Respuesta
- True
- False
Pregunta 62
Pregunta
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.
Respuesta
-
.0000 to .3000
-
.8501 to 1.000
-
.6001 to .7000
-
.3001 to .6000
-
.7001 to .8500
Pregunta 63
Pregunta
Confidence intervals specify
parameter values in advance.
Respuesta
- True
- False
Pregunta 64
Pregunta
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:
Respuesta
-
0.17
-
0.1331
-
0.44
-
0.99
Pregunta 65
Pregunta
Other things being equal, a 90%
confidence interval is wider than a
95% confidence interval.
Respuesta
- True
- False
Pregunta 66
Pregunta
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:
Respuesta
-
6.9 +/- 0.7
-
6.9 +/- 0.92
-
6.9 +/- 0.5
-
6.9 +/- 1.75
Pregunta 67
Pregunta
A t-distribution with 5 degrees of
freedom has less area in the tails
than a standard normal distribution.
Respuesta
- True
- False
Pregunta 68
Pregunta
The following is true about the t-distribution:
Respuesta
-
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
Pregunta 69
Pregunta
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.
Respuesta
- True
- False
Pregunta 70
Pregunta
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:
Respuesta
-
1.321
-
1.319
-
1.717
-
1.714
-
1.645
Pregunta 71
Pregunta
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:
Respuesta
-
(1.73, 8.27)
-
(3.74, 6.26)
-
(-.46, 10.46)
-
(2.89, 7.11)
Pregunta 72
Pregunta
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.
Respuesta
- True
- False
Pregunta 73
Pregunta
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:
Respuesta
-
less than 30
-
greater than 30
-
not equal to 30
-
at least 30
-
at most 30
Pregunta 74
Pregunta
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
Respuesta
-
.67
-
.66
-
.56
-
.33
-
.17
Pregunta 75
Pregunta
In order to compute the p-value from
sample data, we need to know both
the alternative hypothesis and the
level of significance.
Respuesta
- True
- False
Pregunta 76
Pregunta
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.
Respuesta
-
.0301 to .1000
-
.5001 to 1.000
-
.2001 to .5000
-
.0000 to .0300
-
.1001 to .2000
Pregunta 77
Pregunta
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.
Respuesta
- True
- False
Pregunta 78
Pregunta
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.
Respuesta
- True
- False
Pregunta 79
Pregunta
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.
Respuesta
- True
- False
Pregunta 80
Pregunta
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?
Respuesta
-
Reject the claim by rejecting Ho
-
Accept the claim by rejecting Ho
-
Reject the claim by accepting Ho
-
Accept the claim by accepting Ho
Pregunta 81
Pregunta
In statistical process control, if the pvalue
is less than or equal to alpha, we
should conclude the process is under
control.
Respuesta
- True
- False
Pregunta 82
Pregunta
If mu = 40 pounds, sigma = 4 pounds, and
sample size is 36, the LCL and UCL on a
control chart for x would be:
Respuesta
-
38 pounds, 42 pounds
-
28 pounds, 52 pounds
-
38.67 pounds, 41.33 pounds
-
35 pounds, 45 pounds
Pregunta 83
Pregunta
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.
Respuesta
-
.07 to .13
-
.06 to .14
-
.05 to .15
-
.09 to .11
-
.38 to .42
Pregunta 84
Pregunta
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.)
Respuesta
-
25
-
100
-
400
-
200
Pregunta 85
Pregunta
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.
Respuesta
- True
- False
Pregunta 86
Pregunta
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
Respuesta
-
greater than 20%
-
less than or equal to 20%
-
less than 20%
-
not equal to 20%
-
greater than or equal to 20%
Pregunta 87
Pregunta
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%.
Respuesta
-
Accept the claim by rejecting Ho
-
Reject the claim by rejecting Ho
-
Accept the claim by accepting Ho
-
Reject the claim by accepting Ho
Pregunta 88
Pregunta
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
Respuesta
-
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%
Pregunta 89
Pregunta
The t-test for n1 = 15 and n2 = 15 using
paired testing has
Respuesta
-
14 degrees of freedom
-
13 degrees of freedom
-
29 degrees of freedom
-
28 degrees of freedom
-
30 degrees of freedom
Pregunta 90
Pregunta
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:
Respuesta
-
-0.64
-
0.64
-
0.75
-
-0.75
-
3.10
Pregunta 91
Pregunta
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.
Respuesta
- True
- False
Pregunta 92
Pregunta
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?
Respuesta
-
Paired t-test for mean differences
-
Hypothesis test for one proportion
-
regression analysis
-
Independent t-test for mean differences
Pregunta 93
Pregunta
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?
Respuesta
-
Ha: muD = 0
-
Ha: MuD < 0
-
Ha: MuD > 0
-
Ha: MuD does not equal 0
Pregunta 94
Pregunta
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.
Respuesta
- True
- False
Pregunta 95
Pregunta
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:
Respuesta
-
62
-
11.72
-
-62
-
-11.72
Pregunta 96
Pregunta
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
Respuesta
-
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
Pregunta 97
Pregunta
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?
Respuesta
-
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
Pregunta 98
Pregunta
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.
Respuesta
- True
- False
Pregunta 99
Pregunta
In general, the paired samples
method is preferred over the
independent samples method.
Respuesta
- True
- False
Pregunta 100
Pregunta
The t-test for n1 = 15 and n2 = 7 using the
independent samples approach has
(assuming equal population variances)
Respuesta
-
14 degrees of freedom
-
6 degrees of freedom
-
21 degrees of freedom
-
20 degrees of freedom
-
22 degrees of freedom
Pregunta 101
Pregunta
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
Respuesta
- True
- False
Pregunta 102
Pregunta
The best statistic for pi1 - pi2 is p1 – p2.
Respuesta
- True
- False
Pregunta 103
Pregunta
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
Respuesta
-
0.35
-
0.15
-
0.70
-
0.50
-
0.42
Pregunta 104
Pregunta
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.
Respuesta
- True
- False
Pregunta 105
Pregunta
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.
Respuesta
- True
- False
Pregunta 106
Pregunta
The purpose of a scatterplot is to
visually determine if a relationship
exists between two variables.
Respuesta
- True
- False
Pregunta 107
Pregunta
In using the regression model for
forecasting the next value (or an
individual value) of y, the prediction
interval will be
Respuesta
-
the same as the estimating interval
-
narrower than the estimating interval
-
wider than the estimating interval
-
wider or narrower, depending on the data
Pregunta 108
Pregunta
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:
Respuesta
-
-.80
-
+.64
-
-.74
-
either -.80 or +.80
Pregunta 109
Pregunta
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.
Respuesta
- True
- False
Pregunta 110
Pregunta
When R2 = 1, then Se = Sy.
Respuesta
- True
- False
Pregunta 111
Pregunta
A correlation coefficient of –1.0 would
imply that the standard error of the
estimate Se would necessarily be equal
to 0.
Respuesta
- True
- False
Pregunta 112
Pregunta
Standard error is measured in the units
of the x variable.
Respuesta
- True
- False
Pregunta 113
Pregunta
The range of a regression coefficient is
– 1 to + 1.
Respuesta
- True
- False
Pregunta 114
Pregunta
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.
Respuesta
- True
- False
Pregunta 115
Pregunta
If ŷ = 15 + 10x, then the estimated value of
y when x = 5 is:
Respuesta
-
25
-
65
-
10
-
15
-
55
Pregunta 116
Pregunta
When H0 is accepted in a regression
model, we conclude:
Respuesta
-
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.
Pregunta 117
Pregunta
Seasonality can be incorporated into
regression models with dummy
variables.
Respuesta
- True
- False
Pregunta 118
Pregunta
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?
Respuesta
-
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.
Pregunta 119
Pregunta
If a correlation exists between y and x,
then necessarily either y causes x or x
causes y.
Respuesta
- True
- False
Pregunta 120
Pregunta
The advantage of multiple regression
over simple regression is that we can
change more than one variable at a
time.
Respuesta
- True
- False
Pregunta 121
Pregunta
If ŷ = 31 + 1.2x1 – 3.4x2 + 5x3, then the
estimated value of y when x1 = – 6, x2 = 3,
and x3 = 2 is:
Respuesta
-
31.7
-
25.4
-
23.6
-
38
Pregunta 122
Pregunta
The alternative hypothesis in a multiple
regression problem is that no linear
relationship exists between a given
independent variable and y.
Respuesta
- True
- False
Pregunta 123
Pregunta
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?
Respuesta
-
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.
Pregunta 124
Pregunta
Adding another variable to a regression
equation will make R2
Respuesta
-
decrease
-
increase
-
stay the same or increase
-
stay the same or decrease
-
increase, decrease, or stay the same
Pregunta 125
Pregunta
The purpose of R2 adjusted is to
discern the effect of adding a variable
to a model.
Respuesta
- True
- False
Pregunta 126
Pregunta
Adding another variable to a
regression equation will necessarily
make R2 adjusted increase.
Respuesta
- True
- False
Pregunta 127
Pregunta
It is possible for a variable to be
significant in multiple regression when
that same variable is not significant in
simple regression.
Respuesta
- True
- False
Pregunta 128
Pregunta
Stable environments are critical for
effective time series analysis.
Respuesta
- True
- False
Pregunta 129
Pregunta
Which of the following is not a component
of time series?
Respuesta
-
Seasonality
-
Cycle
-
Randomness
-
Trend
-
Contingency
Pregunta 130
Pregunta
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:
Respuesta
-
68.35
-
16.35
-
2.85
-
49.15
-
40
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