Logistic Regression

Question 1

What is odds?

Answer 1

Ratio of the probability of an event occurring to the probability of it not occurring

Question 2

What is odds ratio?

Answer 2

The odds in the group of interest over the odds in the comparator

Question 3

What would hte odds ratio be if there was no difference between the 2 groups?

Answer 3

1

Question 4

What value would the odds ratio be if the odds of the outcome occurring in the group of interest are lower than the comparator group

Answer 4

<1

Question 5

What value would the odds ratio be if the odds of the outcome occurring in the group of interest are greater than the comparator group

Answer 5

> 1

Question 6

What is the equation for simple linear regression?

Answer 6

y = a + bx

(a and b explain linear relationship between y and x)

Question 7

What is “a” in y = a + bx

Answer 7

a is the constant (or intercept point at which regression line crosses y axis)

Question 8

What is “b” in y = a + bx

Answer 8

b is the slope (regression coefficient) and tells us the direction and strength of the relationship

Question 9

What is “y” in y = a + bx

Answer 9

y is the outcome variable (dependent variable or response)

Question 10

What is “x” in y = a + bx

Answer 10

x is the predictor variable (independent or explanatory variable). Using x to predict y.

Question 11

What is the equation for multiple regression when predicting lung function (FEV1) from height (cm), age and ethnicity?

Answer 11

FEV1 = a + b1height + b2age + b3ethnicity

Question 12

Logistic regression works on a ___ scale

Answer 12

log

Question 13

To return to the odds scale, need to _______ the regression coefficients

Answer 13

exponentiate (raising to a power)

Question 14

How do you exponentiate?

Answer 14

Use the natural log (ln) and its base e =2.71828

Question 15

Logistic regression creates bounds so the values all range within the range of…

Answer 15

0 to 1