Using the concept of ‘sanitation-related quality of life’ (SanQoL) to measure what is valued by users

The below post dates from before I had completed the fieldwork for my PhD.

So it’s probably better to read the specific page on SanQoL and the associated papers, rather than the below.

===========================================

Introduction

Since investment options are always compared under a budget constraint, economic evaluation aims to inform unavoidable decisions and support allocative efficiency. Various economic evaluation methods (such as cost-effectiveness analysis and cost-benefit analysis) compare costs and consequences of alternative interventions.

Improvements in sanitation can impact on health, and it is typically health outcomes such as averted deaths and diarrhoea cases which have been valued previous cost-effectiveness analyses. Cost-benefit analyses have gone further, also valuing time savings, productivity and other economic benefits.

The problem

However, none of these economic evaluations have incorporated the broader “quality of life” (QoL) benefits of sanitation, related to privacy, safety, pride, dignity etc.* Some studies call these “intangible”. However, these broader QoL benefits are often the primary demand-side drivers of sanitation investment by poor households.

Therefore, economic evaluations which overlook these outcomes may lead to in misallocated resources. At the very least, they will not fully reflect the value placed on sanitation by users.

Where my PhD research comes in

Can anything be done about this? If there was a quantitative measure of ‘Sanitation-related quality of life’ (SanQoL) that represented people’s valuation of QoL benefits, it could be used as an outcome in cost-effectiveness analysis. Further down the line, a SanQoL measure could potentially facilitate monetary valuation of QoL outcomes in cost-benefit analysis.

Taking the first steps in developing and applying such a measure is 50-60% of my PhD. I’ve kept fairly quiet about it so far while doing lots of reading and initial qualitative work. Now, however, the ideas are clear enough to share, for reflection and critique. I can’t write about interim results, unfortunately. Hopefully I’ll get some abstracts into  academic conferences later in the next year, and then comes papers… but I can write about ideas at least.

This post sets out a bit of my rationale and thinking – in the rest of this post there’s space for two issues, (i) why qualitative grounding is important, and (ii) what distinguishes a psychometric approach from an ‘observer’ approach. How I’m defining and framing QoL itself in all this will have to wait for another post. In short, I’m using Sen’s capability approach. However, I’m  also building on the concept of ‘health-related quality of life’ which is widely used in health economics for valuation of health states in support of quality-adjusted life years.

What do people value about sanitation? The importance of qualitative work

Value is a key concept in economics. Demand for a service in any sector is a derived demand for a stream of benefits valued by the user. For example, demand for healthcare services is a derived demand for health itself. So, demand for household toilets is a derived demand for the benefits of sanitation. These are many and various (see above) so any measure of SanQoL would likely need to be multi-dimensional.

A measure of SanQoL would ideally capture all QoL-related outcomes perceived by as important by users. What are those outcomes? First port of call is looking into the literature, but best practice is to ask people directly in the setting of interest, in support of  validity (amongst other reasons)

The setting in which I plan to test the quantitative measure is low-income settlements of Maputo, Mozambique. Accordingly, I did some qualitative interviews and focus groups with users of different types of sanitation services in 2018. To identify the relative value attached to different ‘attributes’ of SanQoL, I also included some ranking and triadic comparison exercises. More on that once I get the qual. paper written…

Measuring SanQoL quantitatively

Having a rich qualitative description of how people think sanitation relates to ‘a good life’ is important and helpful. However, in order to be practically used in economic evaluation, it requires translation into a quantitative measure. For example, it would be helpful to be able to say “this intervention cost US$ 1,000 per incremental point on the SanQoL scale, as compared to that intervention.” You can’t do this with qualitative data.

Such a SanQoL measure would need to be experiential or psychometric, in that it would be “imposing measurement and number upon operations of the mind”. For a given dimension of SanQoL (privacy, for example) this involves asking people to scale their own level on that dimension, by recalling their experience (e.g. variations on “do you feel like you have privacy”). The non-psychometric way to do this would be an external observer looking at a toilet and scaling the level of privacy provided (e.g. variations on “does this toilet provide adequate privacy”). This ‘observer approach’ measures something fundamentally different, that is, quality of service (or infrastructure) rather than quality of life. Individuals themselves are best-placed to scale their quality of life.

I have developed some questionnaire items on the basis of the qualitative work and will be running a quantitative survey in April, including piloting and cognitive interviews beforehand to make sure the items are well-understood. Of course, even if that work is successful, the measure will not necessarily be valid in other settings. More on all this another time.

Conclusion

I hope that useful insight will come out of this work to inform how sanitation-related quality of life can be measured. My primary purpose is in economic evaluation, but there are many other potential uses of such a measure if it can be validated across settings. I hope to write occasional blogposts on other aspects of SanQoL in due course. Please contact me if you are working in this field as well and want to discuss.

*At least, none have done so quantitatively – Hutton et al.’s East Asia phase 2 studies did so qualitatively.