anova(fit1,fit2)

> anova(fit3,fit4)
Analysis of Variance Table

Model 1: dta$X.U.FEFF..mpist. ~ relevel(factor(dta$matem), 7) + relevel(factor(dta$aidink),
    7) + factor(dta$sukup)
Model 2: dta$X.U.FEFF..mpist. ~ relevel(factor(dta$matem), 7) + relevel(factor(dta$aidink),
    7) + factor(dta$sukup) + factor(dta$HISEI)
  Res.Df     RSS Df Sum of Sq      F Pr(>F)
1    985 3067966
2    929 2857404 56    210562 1.2225 0.1314

> anova(fit3,fit5)
Analysis of Variance Table

Model 1: dta$X.U.FEFF..mpist. ~ relevel(factor(dta$matem), 7) + relevel(factor(dta$aidink),
    7) + factor(dta$sukup)
Model 2: dta$X.U.FEFF..mpist. ~ relevel(factor(dta$matem), 7) + relevel(factor(dta$aidink),
    7) + factor(dta$sukup) + dta$HISEI
  Res.Df     RSS Df Sum of Sq      F  Pr(>F)
1    985 3067966
2    984 3049605  1     18361 5.9244 0.01511 *
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Age     Medication cost
Grp     relative to index
 1   95  103  112  114  110  108
 2  113  126  119  121  144  121
 3  118  127  113  127  124  128
 4  131  111  134  120  140  134
 5  132  160  146  144  159  154
 6  157  176  176  165  170  168