inferential statistics

A baker is interested in whether there is an association between three types of cookies,
and gender of the buyer. He finds the following contingency table, and a significant Chisquare value of 10.584.
Men
Women
Chocolate
11
11
Nuts
22
9
Fruit
8
20
Calculate Cramer’s V for this table.
Answer:
The “Beautiful Pets” fashion show opens with the cat and dog parade, where cats and
dogs appear on stage one after the other to showcase their outfits.
This year the cats and dogs appear in the following order:
C, D, C, D, D, C, C, C, C, D, D, C, D
Where ‘C’ represents a cat, and ‘D’ represents a dog. How many runs were there in this
sequence?
Answer:
You noticed that the bus is a lot more crowded when the weather is bad, and decided to
run a regression analysis of amount of rainfall, and the number of people on the bus.
Below is a table containing the observed number of people on the bus, and the predicted
number of people on the bus predicted by your regression model. The mean number of
people on the bus is 16.
Observed value
Predicted value
23
16.8
16
18.4
10
15.2
15
13.6
Use the values in the tables to calculate the R-squared.
Answer:
A celebrity called Wayne East has been having some money problems recently. He
is thinking of investing in the greatest record in the world, and wants to know
how the value will change over time. He has an exponential regression model
where his predictor is time in months, and response variable is money, measured
in thousands of dollars. The alpha value is 4.2, and beta is 1.03.
Based on this model, how much money (in thousands) will he have after six
months?
Answer:
Based on the Downtown Castle model, calculate the upper boundary of the 95% confidence interval for
the age slope coefficient. You can select the critical t-value from the table.
Answer:
Based on the Downtown Castle model, calculate the lower boundary of the 95% confidence interval for
the age slope coefficient.
Answer:
The company decides to look at three other prizes in addition to cash and vouchers: a car,
a holiday and a computer.
How many dummy variables will the company use in their model?
Answer:
The table below shows the predicted and observed values for 20 voters using the
politician’s logistic regression model.
Predicted
Observed
Vote
Did not vot
Vote
8
1
Did not vote
2
9
Calculate the specificity.
Answer:
You’re still not convinced of your findings about Wayne East’s album, so you decide to do an
experiment on how happy people are after listening to Wayne’s new album, and compare this to a
group that listen to a lecture on Astrophysics. The table below shows the enjoyment levels in both
groups.
Wayne
Astrophysics
2.5
8.0
7.4
5.5
7.2
3.2
6.5
6.2
What is the sum of the ranks in the Wayne group? 19 (this is the correct answers)
Answer:
Based on the table in the previous question, what is the sum of the ranks in the Astrophysics group?
Answer:
Based on comparing the Wayne East and Astrophysics, what is the test statistic if we run a Wilcoxon
rank sum test?
Answer:
The “Beautiful Pets” fashion show opens with the cat and dog parade, where cats and
dogs appear on stage one after the other to showcase their outfits.
This year the cats and dogs appear in the following order:
C, D, C, D, D, C, C, C, C, D, D, C, D
Where ‘C’ represents a cat, and ‘D’ represents a dog. How many runs were there in this
sequence?
Answer:
You noticed that the bus is a lot more crowded when the weather is bad, and decided to
run a regression analysis of amount of rainfall, and the number of people on the bus.
Below is a table containing the observed number of people on the bus, and the predicted
number of people on the bus predicted by your regression model. The mean number of
people on the bus is 16.
Observed value
Predicted value
23
16.8
16
18.4
10
15.2
15
13.6
Use the values in the tables to calculate the R-squared.
Answer: 14.88 is not the correct answer
People seem to have less accidents when there are stop signs around. Your friend measures the
number of stop signs in various neighbourhoods in various cities and finds a negative relationship
when he plots the number of accidents against number of stop signs, combining the results per city.
They tell you that if your street gets a stop sign, there will be fewer accidents.
Which of the following potential pitfalls apply to your friend’s statement?
There is an outlier.
The relationship is not linear.
Correlation is not causation.
Ecological fallacy.
Restriction of range.
Answer:
A celebrity called Wayne East has been having some money problems recently. He
is thinking of investing in the greatest record in the world, and wants to know
how the value will change over time. He has an exponential regression model
where his predictor is time in months, and response variable is money, measured
in thousands of dollars. The alpha value is 4.2, and beta is 1.03.
Based on this model, how much money (in thousands) will he have after six
months?
Answer: