ISYE 6402 MIDTERM PREP

• | Page

ISYE 6402 MIDTERM PREP

ACTUAL EXAM WITH CORRECT SOLUTIONS.

We can assess the constant variance assumption in linear regression by plotting the residuals vs. fitted values. - correct answer- True

If one confidence interval in the pairwise comparison in ANOVA includes zero, we conclude that the two corresponding means are plausibly equal. - correct answer- True

The assumption of normality is not required in linear regression to make inference on the regression coefficients. - correct

answer- False (Explanation: is required)

We cannot estimate a multiple linear regression model if the predicting variables are linearly independent. - correct answer-

False (Explanation: linearly dependent)

If a predicting variable is a categorical variable with 5 categories in a linear regression model without intercept, we will include 5 dummy variables. - correct answer- True

• / 2

• | Page

If the normality assumption does not hold for a regression, we may use a transformation on the response variable. - correct answer- True

The prediction of the response variable has higher uncertainty than the estimation of the mean response. - correct answer- True

Statistical inference for linear regression under normality relies

on large sample size. - correct answer- False (Explanation:

small sample size is fine)

A nonlinear relationship between the response variable and a predicting variable cannot be modeled using regression. -

correct answer- False (Explanation: Nonlinear relationships can

often be modeled using linear regression by including polynomial terms of the predicting variable, for example.)

Assumption of normality in linear regression is required for confidence intervals, prediction intervals, and hypothesis testing. - correct answer- True

• / 2