Good point.
I think it does make some sense for unemployment though as at least some proportion of people will forsee becoming unemployed either because they think they’ll get fired or because they are dissatisfied with their jobs to the point they want to quit.
The data on being disabled it is a bit more troubling, but (without having read the report) one reason might be that this was official registration (or even official diagnosis) for disability which, for disabilities with slow onset (arthritis, some disabling diseases like MS, etc..), there would perhaps be a period of discomfort and pain before becoming officially disabled. Keep in mind that only some proportion of subjects need to have slow onset conditions to skew the average toward a negative dip before diagnosis (governmental or medical)
I tend to agree with you that it is still unclear whether the relationship between ‘raw’ happiness (as mentioned in your post) and perceived happiness is linear or not. Log makes intuitive sense in some ways but the implication that happiness increases linearly with wealth is extremely counterintuitive to me.
I tend think something akin to prospect theory’s weighting happiness relative to some set point may be plausible. I also think there will be some odd effects near the boundaries (0&10).
For me the project we’re trying to push forward with this manifesto is in large part about trying to figure out satisfactory answers to questions like these, so I agree it’s a priority.
Despite these open questions I tend to think it’s useful to proceed as if it were linear for now as that seems to be status quo in the field and to me it seems more intuitive. Even if we’re wrong about linearity this measurement system should lead to more accurate approximations of ‘raw’ happiness than, say, QALYs