1. Constantly forgotten Hein Stigum Presentation, data and programs at:
Talks, Constantly forgotten
Confounding and interaction, Kleinbaum and Kupper, Jægtvolden
Nov-18
Nov-18
H.S. 1

2. Agenda Example Concepts Methods Prevalence, risk and odds
Regression models RD RR OR
Nov-18
Nov-18
H.S. 2

3. Smoking among 10th graders?
What is the probability that my 10th grader is smoking?
Nov-18
Nov-18
H.S. 3

4. Constant term, sex
Constant term, intercept
Nov-18
Nov-18
H.S. 4

5. Constant term, age
Nov-18
Nov-18
H.S. 5

6. Prevalence and risk Prevalence Incidence proportion
Risk of having disease
Incidence proportion
Risk of getting disease
Having a cold
Having a disease prone gene
Nov-18
Nov-18
H.S. 6

7. Generalized linear models, GLM
Smoking as outcome
y=0/1, x = covariates
E(y|x) = P(y=1|x) = p
family: y|x~Binomial
identity RD
link: log RR
logit OR
Nov-18
Nov-18
H.S. 7

8. RD versus RR and OR 1 RD -1 1 
RR, OR
Nov-18

9. Linear binomial model, RD
Variable RD
Confidence interval
Risk at reference
0.000
Sex
Boy
Girl
0.120
(0.107
, 0.132)
Parents marital status
Living together
Single
0.104
(0.088
, 0.119)
Educational plans
Academic
Secondary 3 years
0.057
(0.027
, 0.088)
Secondary 1 year
0.107
(0.069
, 0.145)
Vocational
0.130
(0.113
, 0.147)
Family economy
Well off
Short of mony
0.086
(0.038
, 0.134)
Girl, with single parents,
academic plans and well off:
Prevalence=
=0.223
=22.3%
Nov-18
Nov-18
H.S. 9

10. Log binomial model, RR Girl, with single parents,
Variable RR
Confidence interval
Risk at reference
0.043
Sex
Boy 1
Girl
2.45
(2.21
, 2.72)
Parents marital status
Living together
Single
1.94
(1.77
, 2.12)
Educational plans
Academic
Secondary 3 years
1.55
(1.26
, 1.90)
Secondary 1 year
2.04
(1.68
, 2.46)
Vocational
2.26
(2.05
, 2.48)
Family economy
Well off
Short of mony
1.45
(1.21
, 1.74)
Girl, with single parents,
academic plans and well off:
Prevalence=
0.043 * 2.45 * 1.94=0.203
=20.3%
Nov-18
Nov-18
H.S. 10

11. Odds and probability
Nov-18
Nov-18
H.S. 11

12. Disease frequency depicted
Show:
Prevalence
Incidence proportion, closed pop, no loss to follow up
Incidence rate, takes observation time into account, (could also have loss to follow up)
Nov-18
Nov-18
H.S. 12

13. Logistic model, OR Girl, with single parents,
Variable OR
Confidence interval
Odds at reference
0.039
Sex
Boy 1
Girl
3.01
(2.65
, 3.41)
Parents marital status
Living together
Single
2.30
(2.05
, 2.58)
Educational plans
Academic
Secondary 3 years
1.70
(1.31
, 2.19)
Secondary 1 year
2.44
(1.90
, 3.13)
Vocational
2.82
(2.49
, 3.19)
Family economy
Well off
Short of mony
1.71
, 2.24)
Girl, with single parents,
academic plans and well off:
Prevalence odds=
0.039 * 3.01 * 2.30=0.269
Prevalence=21.2%
Nov-18
Nov-18
H.S. 13

14. Summing up Reporting constant Technical Increases information a lot!
0 must be part of the range
Not for traditional Case Control
Nov-18
Nov-18
H.S. 14