Table 7

Comparisons of linear regression models, with and without outlier, of the natural logarithm of the rate of stomach cancer on the main explanatory variables and each of ten interaction variables. The main effects (ME) comprised the explanatory variables five year period, sex, race, Lauren type, and age. The difference between the residual sum of squares (RSS) before and after the addition of each interaction variable to ME (ΔRSS) was divided by RSS and multiplied by error d.f. to yield F, whose numerator df was 1 and denominator df was error df.

WITHOUT OUTLIER


Model Covariates

RSS

ΔRSS

error df

F

P


ME

50.64

ME + five year period:sex

50.60

0.05

152

0.1

0.71

ME + five year period:race

50.09

0.55

152

1.7

0.20

ME + five year period: Lauren type

50.51

0.13

152

0.4

0.53

ME + five year period:age

50.04

0.60

152

1.8

0.18

ME + sex:race

50.62

0.02

152

0.1

0.82

ME + sex:Lauren type

43.99

6.65

152

23.0

3.9 × 10-6

ME + sex:age

50.63

0.02

152

0.0

0.83

ME + race:Lauren type

45.00

5.64

152

19.0

2.3 × 10-5

ME + race:age

49.50

1.14

152

3.5

0.06

ME + Lauren type:age

31.62

19.03

152

91.5

< 1 × 10 -10

WITH OUTLIER

Model Covariates

RSS

ΔRSS

error df

F

P

ME

58.14

ME + five year period:sex

57.95

0.19

153

0.5

0.48

ME + five year period:race

57.22

0.92

153

2.5

0.12

ME + five year period: Lauren type

57.80

0.34

153

0.9

0.35

ME + five year period:age

57.88

0.25

153

0.7

0.41

ME + sex:race

58.01

0.13

153

0.3

0.57

ME + sex:Lauren type

50.34

7.79

153

23.7

2.8 × 10-6

ME + sex:age

58.11

0.02

153

0.1

0.81

ME + race:Lauren type

51.44

6.70

153

19.9

1.6 × 10-5

ME + race:age

57.50

0.63

153

1.7

0.20

ME + Lauren type:age

36.88

21.25

153

88.2

< 1 × 10 -10


Wachtel et al. BMC Cancer 2006 6:65   doi:10.1186/1471-2407-6-65

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