My outcome variable includes six categories but I'm not sure whether they count as "fully ordered". The categories measure the extent of added value of a certain intervention: 1 (major added value), 2 (considerable added value), 3 (minor added value), 4 (non-quantifiable added value), 5 (no added value), 6 (less value).
My concern is, however, that category 4 (non-quantifiable) is defined as showing that there is added value but that it cannot be quantified because of a lack of data, i.e. the benefit could be either major, considerable or minor. It doesn't mean that category 4 is smaller than category 3 for example.
Would it still be possible to use an ordered logit model given that one of the six categories doesn't really fit in the order? Or can the ordered logit model be discarded even without having tested for proportional odds?