Practice Quiz 2
1) Which of the following formulas would calculate the statistic that is MOST
APPROPRIATE for comparing the variability of two data sets with different
distributions?
Mean/Standard Deviation
This is the inverse of the formula for the coefficient of variation.
Standard Deviation/Mean
correct
This is the formula for the coefficient of variation, the best statistic to compute to
compare the variability of two data sets with different distributions. Dividing by the mean
provides a measure of the distribution’s variation relative to the mean.
Mean-Median
Although the difference between the mean and the median may provide information
about whether a dataset is skewed, it does not provide useful information for comparing
variability across different distributions.
Median-Mean
Although the difference between the mean and the median may provide information
about whether a dataset is skewed, it does not provide useful information for comparing
variability across different distributions.
Mean/Variance
The mean and variance are measured in different units. For example, if the mean is
measured in feet, the variance is measured in square feet. The coefficient of variation is
calculated using the mean and standard deviation, both of which have the same units.
Variance/Mean
The mean and variance are measured in different units. For example, if the mean is
measured in feet, the variance is measured in square feet. The coefficient of variation is
calculated using the mean and standard deviation, both of which have the same units.
, 2) The owner of Boston sports bar believes that, on average, her restaurant is
busier on days when the Red Sox play an away game (a game played at another
team’s stadium), but she wants to be sure before adding more staff. To test
whether this is true, she takes a random sample of 50 days over the course of the
baseball season and records the total daily revenue, along with whether the Red
Sox were playing away that day (1 if yes, 0 if no). Using the data provided,
perform a regression analysis to determine the effect of Red Sox away games on
revenue. Be sure to include the residuals and residual plot in your analysis.
From the Data menu, select Data Analysis, then select Regression. The Input Y Range
is A1:A51 and the Input X Range is B1:B51. You must check the Labels box to ensure
that the regression output table is appropriately labeled. You must also check
the Residuals and Residual Plots boxes so that you are able to analyze the residuals
, 3) The sports bar owner runs a regression to test whether there is a relationship
between Red Sox away games and daily revenue. Which of the following
statements about the regression output is true? SELECT ALL THAT APPLY.
The average daily revenue for days when the Red Sox do not play away is $1,768.32.
CORRECT
This option is true. $1,768.32 is the average daily revenue on days when the Red Sox
do not play away.
The average daily revenue for days when the Red Sox play away is $1,768.32.
This option is false. The average daily revenue on days when the Red Sox play away is
$1,768.32+496.25=$2,264.57.
The average daily revenue for days when the Red Sox play away is $2,264.57.
CORRECT
This option is true. The average daily revenue on days when the Red Sox play away is
$1,768.32+496.25=$2,264.57.
The average daily revenue for days when the Red Sox do not play away is $1,272.07.
This option is false. $1,768.32 is the intercept which represents the average daily
revenue when “Red Sox”=0 (that is, a day when the Red Sox do not play away).
On average, the bar’s revenue is $496.25 higher on days when the Red Sox play away
than on days when they do not.
CORRECT
1) Which of the following formulas would calculate the statistic that is MOST
APPROPRIATE for comparing the variability of two data sets with different
distributions?
Mean/Standard Deviation
This is the inverse of the formula for the coefficient of variation.
Standard Deviation/Mean
correct
This is the formula for the coefficient of variation, the best statistic to compute to
compare the variability of two data sets with different distributions. Dividing by the mean
provides a measure of the distribution’s variation relative to the mean.
Mean-Median
Although the difference between the mean and the median may provide information
about whether a dataset is skewed, it does not provide useful information for comparing
variability across different distributions.
Median-Mean
Although the difference between the mean and the median may provide information
about whether a dataset is skewed, it does not provide useful information for comparing
variability across different distributions.
Mean/Variance
The mean and variance are measured in different units. For example, if the mean is
measured in feet, the variance is measured in square feet. The coefficient of variation is
calculated using the mean and standard deviation, both of which have the same units.
Variance/Mean
The mean and variance are measured in different units. For example, if the mean is
measured in feet, the variance is measured in square feet. The coefficient of variation is
calculated using the mean and standard deviation, both of which have the same units.
, 2) The owner of Boston sports bar believes that, on average, her restaurant is
busier on days when the Red Sox play an away game (a game played at another
team’s stadium), but she wants to be sure before adding more staff. To test
whether this is true, she takes a random sample of 50 days over the course of the
baseball season and records the total daily revenue, along with whether the Red
Sox were playing away that day (1 if yes, 0 if no). Using the data provided,
perform a regression analysis to determine the effect of Red Sox away games on
revenue. Be sure to include the residuals and residual plot in your analysis.
From the Data menu, select Data Analysis, then select Regression. The Input Y Range
is A1:A51 and the Input X Range is B1:B51. You must check the Labels box to ensure
that the regression output table is appropriately labeled. You must also check
the Residuals and Residual Plots boxes so that you are able to analyze the residuals
, 3) The sports bar owner runs a regression to test whether there is a relationship
between Red Sox away games and daily revenue. Which of the following
statements about the regression output is true? SELECT ALL THAT APPLY.
The average daily revenue for days when the Red Sox do not play away is $1,768.32.
CORRECT
This option is true. $1,768.32 is the average daily revenue on days when the Red Sox
do not play away.
The average daily revenue for days when the Red Sox play away is $1,768.32.
This option is false. The average daily revenue on days when the Red Sox play away is
$1,768.32+496.25=$2,264.57.
The average daily revenue for days when the Red Sox play away is $2,264.57.
CORRECT
This option is true. The average daily revenue on days when the Red Sox play away is
$1,768.32+496.25=$2,264.57.
The average daily revenue for days when the Red Sox do not play away is $1,272.07.
This option is false. $1,768.32 is the intercept which represents the average daily
revenue when “Red Sox”=0 (that is, a day when the Red Sox do not play away).
On average, the bar’s revenue is $496.25 higher on days when the Red Sox play away
than on days when they do not.
CORRECT
