Final-lecture 16

Question 1

What do logistic and linear regression try to do?

Answer 1

-predict the DV based on one or more independent variables

Question 2

What does linear regression model?

Answer 2

-interval-ratio dependent variable

Question 3

What does logistic regression model?

Answer 3

• categorical variables

- creates a linear regression using dummy variables

Question 4

What are the two types of logistic regression?

Answer 4

• binary logistic regression

- multinomial (polychotomous) logistic regression

Question 5

What is binary logistic regression?

Answer 5

• when dependent categorical variables have two possible outcomes
• dependent variable becomes a dichotomous dummy variable coded as 0 and 1

Question 6

What is a multinomial logistic regression?

Answer 6

• categorical variable with more than two categories

- not within our class though

Question 7

Why use logistic regression?

Answer 7

• many important research topics in sociology for which the dependent variable has been coded as a dichotomous nominal variable
• did you vote (yes or no)

Question 8

What happens when the dependent variable is categorical?

Answer 8

-the assumption of linearity between the DV and IV that is assumed in OLS regression is violated

Question 9

Can we use mean in logistic regression?

Answer 9

-no

Question 10

How are logistic regression results interpreted?

Answer 10

-using OR

Question 11

What is the common logarithm?

Answer 11

-base 10

Question 12

Why do we have to use logistic regression and not linear for a dichotomous dependent variable?

Answer 12

• because logistic regression fits the line in between 0 and 1
• since probability of an event ranges from 0 to 1

Question 13

What type of curve does the logistic regression model use?

Answer 13

• s-shaped

- sigmoid or logistic curve

Question 14

Does b in logistic regression have a clear cut interpretation?

Answer 14

• no

- since it is a curvilinear relationship between probability and X

Question 15

How do we linearize the logistic regression model?

Answer 15

-transforming the dependent variable from probability to logit

Question 16

What is the logit in the formula called?

Answer 16

• a link function since it provides a linear transformation

- logistic regression is considered a generalized linear model

Question 17

How do OLS and logistic regression relate in interpretation?

Answer 17

• relationship is linear for both
• thus, a and b coefficients are interpreted the same way
• but Y-axis is logits

Question 18

What is b in logistic regression?

Answer 18

-the amount of change in the predicted log odds for a one unit change in the independent variable

Question 19

What does a tell us in a logistic regression?

Answer 19

-the value of the log odds when X is zero

Question 20

What do we do to b to make it more sensible?

Answer 20

-anti log it so that it is the effects on the odds scale