[R-lang] Coding

[Peter Graff]

Dear R-lang,

I have a question regarding the interpretation of different coding 
schemes in a regression model. My experiment compares 8 different levels 
of a single independent variable. Additionally, it is possible to 
conceive of 4 of these 8 levels as a mini-2x2 within the 8 level variable:

Cells: A, B, C, D, E-1, E-2, F-1, F-2

I hypothesize the following ordering (which is substantiated by the 
overall means in the different conditions):

ABC>D>E1>F1>E2>F2

Additionally, I hypothesize that E>F and 1>2. I have implemented 2 
different models to test these hypotheses and I would like to hear your 
take on what the correct interpretation of the results is. In model 1 
have have Helmert-coded the hypothesized ordering in terms of the 
following five contrasts:

ABCvDE1F1E2F2
DvE1F1E2F2
E1vF1E2F2
F1vE2F2
E2vF2

All Helmert-contrasts are significant. In model 2 I have used the 
following contrasts instead:

ABCvDE1F1E2F2
DvE1F1E2F2
EvF
1v2

All contrasts except EvF are significant. Collinearity is minimal in 
both models (all correlations below |.2|)

Is it fair to say that the ABC>D>E1>F1>E2>F2 has been substantiated by 
the experiment and thus infer that E>F, even though the EvF contrast is 
not significant in a differently coded model?

Thank you very much in advance for your help,

Best,

Peter Graff