Yeah, that's one of the reasons why I suggested a hybrid of seeking employment and household income. It is similar to the one used by the study, except the article seems to use individual income rather than household income. Of course, there are still problems with that approach. For example: a baseline household income makes many assumptions about a decent standard of living, it would also be complicated to calculate due to variations in household size/composition and regional differences in the cost of living.

That being said, "seeking employment" is likely one of the worse indications of unemployment. People may be excluded or impeded from joining the workforce for a variety of reasons and stop seeking employment because of that. It is a rather long list: discrimination (age, disability, gender, race), accommodations for disabilities, access to affordable childcare, criminal record, level of education. While some of those can be addressed, they rarely are addressed in a meaningful manner. In those cases I find it difficult to treat not-seeking employment as a choice.