Research question: Does gender affect smoking habits?

Hypothesis: A higher proportion of men smoke than women.

fre cgtsmke.
RECODE cgtsmke (1 2=1)(3 thru 5=0) into cgtsmke_dummy.
VARIABLE LABELS cgtsmke_dummy ‘Smokes or not’.
VALUE LABELS cgtsmke_dummy 0’No’ 1’Yes’.
fre cgtsmke cgtsmke_dummy.

fre gndr.
RECODE gndr (1=1)(2=0) into gndr_dummy.
VARIABLE LABELS gndr_dummy ‘Gender dummy’.
VALUE LABELS gndr_dummy 1’Male’ 0’Female’.

LOGISTIC REGRESSION cgtsmke_dummy WITH gndr_dummy.

1-smokes
0-does not smoke.
1-male
0-female

b0: the log odds for category 1 of the dependent variable when the independent variable’s category is 0

b0: the log odds of smoking among women is -1.247.

b1: how much larger or smaller the log odds become as the independent variable increases by 1 unit.

b1: The log odds of smoking are -1.247 for females, but it increases by 0.784 if the respondent is male. The effect of gender on smoking is significant on the 5% significance level. In other words: the log odds of smoking among men are 0,784 times as high as among women.

b0+b1: the log odds for category 1 of the dependent variable when the independent variable’s category is 1.

b0+b1: the log odds of smoking among men is -0,463. (b0+b1*X=-1,247+0,784*1=-0,463)

Exp(B) for b1: is the odds ratio. -> category 1 … times than … category 0.

The odds of smoking are 2.191 times higher for males than for females.

The odds of smoking are (2.191-1)*100=119.1 % higher for males than for females.

Exp(B) for b0: the odds of smoking among women are 0,287.

Conclusion: The results support our hypothesis, stating that “A higher proportion of men smoke than women.” Why? Because the p-value of b1 is higher than 0,05 and the value of the Exp(b1) shows that the proportion of smokers among men is higher than among women.