This assignment uses the ‘effects’ package in R. This package requires you to have an R version of 3.5 or
higher. Update R to the latest version if you have a R version that is not 3.5 or higher. To update R to the
latest version, perform the following:
Open R and in a blank editor, type the following:
In the Menu options in R, you will see a new option entitled ‘installr’.
Select ‘installr’ à Update R and step through the installation steps to update your R version to either 3.5
or a higher version.
To run the code in the book, you will need to install the ‘effects’ and ‘carData’ packages.
This problem will use the scenario from one of the case studies from Chapter 7.
a. Read the first five paragraphs of Example 7.10 on p.p. 290-291 to familiarize yourself with the
data and the scenario.
b. Using the output from the Anova() test on p. 292, what is the p-value that is associated with
variable checks testing? That is, what does that p-value mean in the context of the problem?
c. Using the output from the coeftest() on p.292, interpret the coefficient for the variable checks.
d. Using the output from the coeftest() on p. 292, what is the reference level for the variable Year?
e. Build the same model that the text does but make the reference level for Year 2000. Copy and
paste your code below. You do not have to show any model output, only the code you used to
complete this task.
f. Using the model that the text uses (not the one in part e), determine if the model (the model
with all the variables the text uses) is a good fit for the data. State whether or not the model is a
good fit for the data and provide any R output to support your answer.
g. Build a logistic model like the one specified on p. 292, instead of what the text does, build the
model with no interactions (main effects only).
Using this model, find the probability of release for the third observation in the data. Provide
your R code that shows the glm() function you used, provide the output you need to perform
the probability computation and show your work for the probability of release computation for
the third observation.
h. Read the entire case study. What did you learn from reading this case study? That is, what
analytical techniques did this case study reinforce from the class? The effects plots are
analogous to the full model plots that we looked at during the third Executive Session. That is,
you can interpret the effects plots in the same manner as we did the full model plots.
Do not copy any sentences from the text. Simply state in your own words some analytical
method/technique that you ‘took away’ from reading the case study.
These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction
of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice.
Unethical use is strictly forbidden.
a. Read the first five paragraphs of Example 7.10 on p.p. 290-291 to familiarize yourself with the data and the scenario.
b. Using the output from the Anova() test on p. 292, what is the p-value that is associated with variable checks testing? That is, what does that p-value mean in the context of the problem?
Answer: p-value is <2e-16, that shows coefficient of checks variable is significantly relevant and not equal to 0....