checkVars function

Check Tow Formula Terms for Potential Problems.

Is is checked whether 'term2' is different from 'term1' in adding information to the model. If both are main factors, i.e. no interactions terms, it is checked whether levels of 'term2' differ from those of 'term1'. Otherwise, 'term2' is an interaction with a part being different from 'term1'.

checkVars(Data, term1, term2)

Arguments

• Data: (data.frame) containing all variables of 'term1' and 'term2'
• term1: (character) term of a model formula as returned by 'attr(terms(form), "term.labels")')
• term2: (character) 2nd term of a model formula as returned by 'attr(terms(form), "term.labels")') to check against 'term1'

Returns

(list) with components "Diff"=part of 'term2' distinguishing it from 'term1', "AddInfo"=message informing about potential problems with 'term2'

Author(s)

Andre Schuetzenmeister andre.schuetzenmeister@roche.com