ISYE6414 Midterm 2 Questions and Answers well Explained Latest 2024/2025 Update 100% Correct.
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ISYE6414
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The _______________ for multiple linear regression do not have constant variance. - sample
residuals
How much all the values in the model change when the ith value is removed is known as what? -
Cook's distance
The ______________ for multiple linear regression have constant variance. - error te...
The _______________ for multiple linear regression do not have constant variance. - sample
residuals
How much all the values in the model change when the ith value is removed is known as what? -
Cook's distance
The ______________ for multiple linear regression have constant variance. - error terms
QQPlot and histogram are used to assess what in MLR? - normality
Residuals vs predictor are used to predict what in MLR - linearity
Residuals vs fitted values are used to assess what in MLR - constant variance and independence
Points that are far from the mean of the x's are called - leverage points
Points that are far from the mean of the x's and y's are called - Influential points
It is good practice to perform regression analysis with and without what? - outliers
What is used to quantify outliers? - Cook's distance
Cooks distance that should be investigated. - D_i > 4/n or D_i > 1 or Large D
The proportion of variability in Y than can be explained by the predictor variables. - R-Squared
, Model variables used to account for selection bias. - Controlling factors
Continuous variables are converted to ________ when there is a distinct gap in a variable distribution. -
Indicator variable
The number of degrees of freedom for a T test for the statistical significance of a MLR coefficient? -
n-p-1
.
When testing subsets of coefficients using anova command. - order matters
When can "year" be used as a qualitative variable? - If the variable is not very granular
Used to evaluate the relationship between any two qualitative variables. - Pearson Chi-squared
test
A command needed prior to running a pearson chi-squared test of qualitative variables. - table
What should you do when you have a high number of predicting variables due to a large number of
categorical variables resulting in numerous dummy variables. - Reduce the dummy variables into
groups
Which category does R choose as the baseline label when creating dummy variables with as.factor() -
The first
If you use a model without an intercept, how will interpreting coefficients be different? - No
baseline for comparison
The statistical significance of a predicting variable in a marginal and conditional models are
_____________ . - independent
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