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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.

From: Different regression equations relate age to the incidence of Lauren types 1 and 2 stomach cancer in the SEER database: these equations are unaffected by sex or race

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
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