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WorksheetsR-Matey -- Exam #2 Review
Total questions: 21
Worksheet time: 11mins
Which one of the following commands does not allow descriptives to be generated by group?
by()
aggregate()
with()
All answers generate descriptives
Which of the following packages provides graphing functions that allow "conditioning" on one or more factors?
lattice package
car package
psych package
None of these are correct
The formula syntax uses the (fill in the blank) to separate the response variables on the left from the explanatory variables on the right
|
:
~
None of these answers are correct
The default when using the histogram() function is a graph of the (fill in the blank) within in each group.
Counts
Proportions
Frequencies
None of the answers are correct
The histogram() function allows you to condition on (fill in the blank) factor(s).
one
two
three
all of these are correct
"Conditioning" is indicated with which one of the following symbols?
~
$
|
%
The bwplot() from the lattice package is similiar to boxplot() except that it also allows you to (fill in the blank).
condition on factors
plot additional deciles
extrapolate
none of these answers are correct
If you wanted to test whether group size varied between groups, you could run which of the following statistical tests?
F-test
t-test
chi-squared test
none of these are correct
Statistical tests help us to identify (fill in the blank) differences not due to minor variation in the data
uncertain
real
imaginary
none of these are correct
A t-test will test which of the following for statistical significance?
Comparing the standard deviations between exactly 2 groups
Comparing the medians between exactly 2 groups
Comparing the means between exactly 2 groups
None of these answers are correct
Many statistical tests assume that the data follows a (fill in the blank) distribution.
normal
uniform
exponential
all of these are correct
To test the statistical differences between 3 or more means you can use which of the following tests?
t-test
Z-test
ANOVA
All of these answers are correct
In order for ANOVA to test which model is better, the models must be (fill in the blank).
the same size
nested
repeatable
none of these are correct
In linear modeling, the model outcome is also called the (fill in the blank).
explanatory variable
response or dependent variable
independent variable
all of these are correct
A driver, in a key driver analysis, only implies which of the following?
causation
association
similarity
none of these are correct
Which of the following are alternative names for linear modelling?
Regression analysis
Linear regression analysis
Least squares fitting
All of these are alternative names
Which of the following is not a step in the linear modeling process
Inspecting your data
Transforming your data
Checking relationships between the variables
All of the above are steps
Checking correlation between the variables prior to linear modeling is an important step. Which of the following might trigger concern?
r>0.5
r<0.6
r>0.9
r<0.3
Which for the following is a true statement in comes to the development of linear models?
Residual values should be normally distributed
Skewed data is fine for use in developing linear models
The optimal model maximizes the distances between the line and the data points
Data should be standardized before being transformed
Which function graphs the 95% confidence intervals for the all of the estimated model coefficients for sat.model?
plot(sat.model)
coefplot(sat.model)
bwplot(sat.model)
all of these will work
Which is false about the R-squared value calculated for a given linear model?
It measures the amount of variation explained by the model
It will never be smaller then the Adjusted R-squared value
It is unrelated to correlation
None of the above these are false
