Statistical modelling
For the analysis for the complete period of 60 days the second diet is now represented as A+B, not A+D, in view of the mistake by the technician. The residual mean square in this case is 1653 g2, slightly higher than for the 30-day period. Also, over the 60-day period the differences between diets were slightly lower than during the first 30 days. In both cases there was no overall significant difference among diets. Indeed, the results for the two diets C and B, which were fed as directed, were very similar.
Analysis of variance (adjusted for covariate)
Source
|
d.f.
|
s.s.
|
m.s.
|
v.r.
|
F pr.
|
Batch stratum
|
Covariate
|
1
|
32310
|
32310
|
|
|
Batch.*Units* stratum
|
Diet60
|
2
|
4313
|
2157
|
1.30
|
0.305
|
Covariate
|
1
|
85893
|
85893
|
51.95
|
<.001
|
Residual
|
13
|
21492
|
1653
|
4.64
|
|
Total
|
17
|
154607
|
|
|
|
|
|
|
|
|
|
Grand mean
|
198.0
|
|
|
|
|
Diet60
|
C
|
A+B
|
B
|
|
|
|
188.4
|
219.9
|
185.7
|
|
|
rep.
|
6
|
|
|
|
|
d.f.
|
13
|
|
|
|
|
s.e.d.
|
23.92
|
|
|
|
|
|