HBX final
Suppose we want to assign dummy variables to the seasons (Winter, Spring, Summer,
Fall). How many dummy variables do we need? - answer3
If the developer wanted to create a regression model to predict housing starts from all
the other financial variables, which of the following would be INDEPENDENT variables?
(Select all that apply.) - answer It’s all the variables that make up the price during the
year...
The variables for location and wine consumption are collinear. VS:
The variable for location is a better predictor than wine consumption. - answer The first
is true of this manager's shitty regression analysis experiments because that's what
happens when the coefficient for one variable is no longer significant and the other
variable's R-squared value goes up, yet the adjusted R-squared has decreased.
average vs average IF
(Don't forget descriptive statistics)
~mean - answerAverageIF is a conditional, limiting scope to something. Like if we're
looking for the average IF so and so is doing something...
square root of variance = standard dev. - answer
scatterplot showing a downward 'slope' (really dots descending); some more clumped
on each end, few in middle. What's the likely correlation?
-.8, -.2, .2, or .8? - answer-.8
watch for ':' vs ',' - answer
If the prices are listed in cells A2:A26, which of the following Excel functions would
calculate the 95th percentile? - answerPERCENTILE.INC(A2:A26,0.95)
NOT "0.05"!!!
For a sample with x =15, s=2, and n=25, which of the following formula would calculate
the upper bound of the 95% confidence interval for the true population mean? -
answer=15+CONFIDENCE.T(0.05,2,25)
NOT
=15+CONFIDENCE.T(0.025,2,25)
A popular hair salon wants to gather data about how returning customers rate the
quality of the service they received during their most recent appointment. The owner
, decides to use a survey to gather this data. What is the BEST option for selecting
respondents to the survey? - answerRandomly select a sample of returning customers
from appointment records and mail them a survey.
NOT:
Phone interview,s in person surveys during appointments... or paper surveys near the
entrance. duh tothe last two
Assuming that all else remains constant, what happens to a confidence interval around
the mean if we raise the sample size from 25 to 100?
Does the width and confidence level narrow or widen? - answerNarrows!
The manager runs a two-sided hypothesis test to determine if the number of pints
produced has changed. The p-value of the test is 0.238. What does this say about ice
cream production? - answerIf there were no actual change in the average number of
pints of ice cream produced daily, the chance of seeing average ice cream production
as low as 13,518 pints would be 23.8%.
NOT
The manager should expect to produce more than 13,518 pints of ice cream on 23.8%
of the days that the factory is running.
statistically significant but not explain a large percentage of the variation between the
two variables - answerLow R-squared, Low p-value
what happens to the average selling price of a house when house size increases by 500
square feet. - answerAverage selling price would increase by approximately $127,500
the trick is that it's not asking what the total selling price is, but what the average selling
price is... average selling price WHEN such and such is increased.
y=a+bx, which of the following describes y?
slope? intercept? value we're trying to predict?
expected value of dependent variable? what about independent variable? - answerThe
expected value of the dependent variable
The value we are trying to predict
NOT THE INTERCEPT!!!!! Not the slope. Not independent variable..
When analyzing a residual plot, which of the following indicates that a linear model is a
good fit? - answerRandom spread of residuals around the x-axis
Suppose we want to assign dummy variables to the seasons (Winter, Spring, Summer,
Fall). How many dummy variables do we need? - answer3
If the developer wanted to create a regression model to predict housing starts from all
the other financial variables, which of the following would be INDEPENDENT variables?
(Select all that apply.) - answer It’s all the variables that make up the price during the
year...
The variables for location and wine consumption are collinear. VS:
The variable for location is a better predictor than wine consumption. - answer The first
is true of this manager's shitty regression analysis experiments because that's what
happens when the coefficient for one variable is no longer significant and the other
variable's R-squared value goes up, yet the adjusted R-squared has decreased.
average vs average IF
(Don't forget descriptive statistics)
~mean - answerAverageIF is a conditional, limiting scope to something. Like if we're
looking for the average IF so and so is doing something...
square root of variance = standard dev. - answer
scatterplot showing a downward 'slope' (really dots descending); some more clumped
on each end, few in middle. What's the likely correlation?
-.8, -.2, .2, or .8? - answer-.8
watch for ':' vs ',' - answer
If the prices are listed in cells A2:A26, which of the following Excel functions would
calculate the 95th percentile? - answerPERCENTILE.INC(A2:A26,0.95)
NOT "0.05"!!!
For a sample with x =15, s=2, and n=25, which of the following formula would calculate
the upper bound of the 95% confidence interval for the true population mean? -
answer=15+CONFIDENCE.T(0.05,2,25)
NOT
=15+CONFIDENCE.T(0.025,2,25)
A popular hair salon wants to gather data about how returning customers rate the
quality of the service they received during their most recent appointment. The owner
, decides to use a survey to gather this data. What is the BEST option for selecting
respondents to the survey? - answerRandomly select a sample of returning customers
from appointment records and mail them a survey.
NOT:
Phone interview,s in person surveys during appointments... or paper surveys near the
entrance. duh tothe last two
Assuming that all else remains constant, what happens to a confidence interval around
the mean if we raise the sample size from 25 to 100?
Does the width and confidence level narrow or widen? - answerNarrows!
The manager runs a two-sided hypothesis test to determine if the number of pints
produced has changed. The p-value of the test is 0.238. What does this say about ice
cream production? - answerIf there were no actual change in the average number of
pints of ice cream produced daily, the chance of seeing average ice cream production
as low as 13,518 pints would be 23.8%.
NOT
The manager should expect to produce more than 13,518 pints of ice cream on 23.8%
of the days that the factory is running.
statistically significant but not explain a large percentage of the variation between the
two variables - answerLow R-squared, Low p-value
what happens to the average selling price of a house when house size increases by 500
square feet. - answerAverage selling price would increase by approximately $127,500
the trick is that it's not asking what the total selling price is, but what the average selling
price is... average selling price WHEN such and such is increased.
y=a+bx, which of the following describes y?
slope? intercept? value we're trying to predict?
expected value of dependent variable? what about independent variable? - answerThe
expected value of the dependent variable
The value we are trying to predict
NOT THE INTERCEPT!!!!! Not the slope. Not independent variable..
When analyzing a residual plot, which of the following indicates that a linear model is a
good fit? - answerRandom spread of residuals around the x-axis
