LOGIT CRIB SHEET

 

 

Z Score       beta / standard error

 

 

 

Wald Test   (beta / standard error)2 compared with Chi-square @ 1 d.f.

 

 

 

95% Confidence Interval        beta ± (1.96 *  standard error)

 

 

 

Calculation of probability in logit

 

Add up the linear predictor      LP = b0 + b1 +….+bk

 

Take the anti-log of LP (think of this as the odds ratio)

 

Calculate the probability from the odds  p = odd/(1+ odds)

 

 

Chi-square

 

 
Probability

 

 

.05

.01

.001

df

 

 

 

1

3.84

6.63

10.83

2

5.99

9.21

13.81

3

7.81

11.34

16.27

4

9.49

13.28

18.47

5

11.07

15.09

20.52

 

Source: Cambridge Elementary Statistical Tables.