Today’s blog entry will discuss a philosophical issue that has implications for choice of ICECAP instrument and these views are purely my own, not those of any other individual involved in development of any of the ICECAP instruments. The issue concerns the difference in attributes (dimensions/domains) between ICECAP-O (technically designed only for older people) and ICECAP-A (designed for adults of any age).
Now, in many ways the issue is moot: there is considerable overlap in the underlying conceptual attributes and three of the five are pretty much the same. Whilst published work showed ICECAP-O working well amongst older people in a large survey conducted in Bristol, UK, unpublished follow-on work showed it working equally well among the younger adults. Furthermore a national online valuation exercise plus survey conducted in Australia (published in the BWS book) showed it working well there among adults of all ages too.
However, the other two attributes (doing things that make you feel valued and concerns about the future in ICECAP-O vs achievement & progress and feeling settled & secure in ICECAP-A) are arguably different. It might reflect the priorities of different generations: younger generations may feel a great need to achieve and progress – the idea of “moving forward” may be driving this (particularly since we have many more people working in that group). ICECAP-O on the other hand stresses the act of doing things that make you feel valued in life, which (to me) does not necessarily imply “moving forward” (though my personal career changes may have coloured my views!).
Likewise in ICECAP-A feeling settled and secure may reflect current younger generations’ feelings of instability in a world of zero-hour contracts etc. ICECAP-O asks instead about “concerns about the future”. Whilst it might be seen merely as the ICECAP-A question “flipped”, it is phrased with respect to the amount of concern overall, unlike ICECAP-A which is phrased with respect to how many areas of life – there’s a subtle difference there. To illustrate, I will simply pose a question. If you otherwise have a very good quality of life, can you still have a lot of concern about the future? I’d argue yes. Now let’s think about ICECAP-A. If you otherwise have a very good quality of life, can you feel settled and secure in only a few areas of life? Playing devil’s advocate, it could be argued that “this respondent has already said they’re doing well on the other four attributes of quality of life – they have a lot of capability to achieve the levels they want – so how can they feel unsettled in key attributes too?”
Ultimately these are empirical issues, requiring researchers to look at correlation matrices of actual answers. In the Australian survey 5002 people were randomised to either ICECAP-O or ICECAP-A. The Spearman rank correlation coefficients of the respondents’ five tickbox answers were uniformly higher for any given pair of attributes in ICECAP-A compared to their ICECAP-O equivalent. However, a big caveat here is that the ICECAP-O arm was a properly done valuation exercise in which quota sampling – on the basis of own ICECAP-O tickbox answers – was done. There were no previous ICECAP-A data on which to choose quotas. Thus this is not a like-for-like comparison and ICECAP-O therefore had an artificial advantage. Using the Bristol adult ICECAP-O data (to correct, somewhat, for this) caused four of the ten pairwise correlations to be smaller for ICECAP-A but two of these were for attributes common to both instruments. Comparisons among groups from the same country and using the same sampling is therefore required before firm conclusions can be made.
Finally, it is worth considering the philosophy here and I’ll raise a final point. OK it seems that adding younger adults to the valuation sample has changed at least one and arguably two attributes. It raises the normative question of whether we should use these attributes in valuing their quality of life when they haven’t, by definition, lived a long life: perhaps age brings wisdom and it is the older people who “know what’s best for you”. Most people experience regret at some point and our “values” (defined both conceptually – the attributes themselves – and numerically – the tariff) can change with experience.
Of course using a single ICECAP instrument – ICECAP-O if one were persuaded of the above philosophical argument – would make things nicer and easier when it comes to “a single common denominator for valuation” but if, like me, you are keen for greater investigation of (and possibly use of) individual valuation, could we justify using ICECAP-O scoring for a 30 year old which may downweight “doing things that make you feel valued” because that person actually is more interested in achieving things and progressing (forward?) in life? On the other hand, knowing what are the key conceptual attributes of ICECAP-A, maybe stressing, in the intro for ICECAP-O, that “doing things that make you feel valued” can easily encompass “achieving and progressing in life” is a practical solution?
Another empirical issue!
And so we come full circle to whether practical solutions, or stricter ones fitting some theory, are the way forward. As usual in health economics, normative issues galore.