Thank you Dason, you're right.

I did it another time, but i'd like someone to comment on this. I wrote the test using the coding example from the website below:

https://personality-project.org/r/r.anova.html
> aov.ex2 = aov(klak$N.cases.~klak$season*klak$year)

> summary(aov.ex2)

Df Sum Sq Mean Sq F value Pr(>F)

klak$season 3 877.7 292.56 7.179 0.0435 *

klak$year 1 32.0 32.00 0.785 0.4256

klak$season:klak$year 3 253.0 84.33 2.070 0.2470

Residuals 4 163.0 40.75

I am a bit confused with it. Can someone write the correct R code?

Those results seem to be intuitively correct, because if I run a one way ANOVA for the klak$season, i get an p=0.0274 * and for klak$year an p=0.63.

Is it appropriate to substitute the 2way anova for the 2 separate one way ANOVA if I cannont calculate the p value, because of the degrees of freedom?