[External] Possible bug
... and just a note, use the data argument in aov (and lm and other modeling functions): aov(uptake ~ Plant * Treatment, data = CO2) Makes the code more readable. Also note, you probably meant ~Plant + Treatment, as interactions are meaningless here. See ?lm for the syntax of model specification. Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Thu, Mar 17, 2022 at 11:10 AM Richard M. Heiberger <rmh at temple.edu> wrote:
with(CO2, table(Treatment, Plant))
Plant Treatment Qn1 Qn2 Qn3 Qc1 Qc3 Qc2 Mn3 Mn2 Mn1 Mc2 Mc3 Mc1 nonchilled 7 7 7 0 0 0 7 7 7 0 0 0 chilled 0 0 0 7 7 7 0 0 0 7 7 7
Plants are nested within Treatments. Hence when Plant is first, it picks up the effect of Treatment. You can see that in the sums of squares and degrees of freedom from both ANOVA tables.
summary(aov(CO2$uptake~CO2$Treatment*CO2$Plant))
Df Sum Sq Mean Sq F value Pr(>F) CO2$Treatment 1 988 988.1 14.685 0.000269 *** CO2$Plant 10 3874 387.4 5.757 2.66e-06 *** Residuals 72 4845 67.3 --- Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
summary(aov(CO2$uptake~CO2$Plant*CO2$Treatment))
Df Sum Sq Mean Sq F value Pr(>F) CO2$Plant 11 4862 442.0 6.569 1.84e-07 *** Residuals 72 4845 67.3 --- Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
On Mar 17, 2022, at 10:17, konrad via R-help <r-help at r-project.org> wrote: summary(aov(CO2$uptake~CO2$Plant*CO2$Treatment))'
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