How not to measure sexual risk aversion

Risk aversion seems like such a simple concept - it is how much people want to avoid risk. Conventionally, economists measure the degree of risk aversion of a person by how much of an expected payoff they are willing to give up for a payoff that is more certain (or entirely certain). If you're willing to give up a lot, you are very risk averse, and if you are not willing to give up a lot, you are not very risk averse. But notice that the measure of risk aversion is all about behaviour, either as a stated preference (what you say you would do when faced with a choice between a more certain outcome, and a less certain outcome that has a higher payoff on average) or a revealed preference (what you actually do when faced with that same choice).

So, I was interested to read this recent paper by Stephen Whyte, Esther Lau, Lisa Nissen, and Benno Torgler (all from Queensland University of Technology), published in the journal Applied Economics Letters (sorry, I don't see an ungated version). In the paper, the authors claim to be comparing "risk attitudes towards unplanned pregnancy and sexually transmitted diseases (STDs)" between health students and other students. It is an interesting research question, since you might expect health students to be better informed about the actual risks of sexual behaviour.

However, when you look at the measure they used for risk attitudes, it becomes immediately clear that there is a problem:

To assess participant perceptions of the safety of different forms of contraception and sexual contact in relation to unplanned pregnancy and STDs, they were asked to rate, on a seven-point scale from 0% safe to 100% safe, the level of safety of each of six options. The six responses were then summed and divided by the number of responses to create a measure of average individual attitudes towards the specific risk.

The six options for risk of unplanned pregnancy were condoms; contraceptive pill; sex during menstruation; intrauterine devices; withdrawal method; and contraceptive implant; and the six options for risk of STDs were oral sex; physical contact; kissing; digital penetration; anal penetration; and vaginal penetration. At least, I think that's the case, as it was a little unclear from the paper.

However, their measure is clearly not a measure of risk attitudes (or risk aversion) at all. It is a measure of 'perceptions of safety'. Notice that the measure doesn't ask about students' sexual behaviour at all, and doesn't ask about a trade-off decision. So, it won't tell you much at all about risk aversion. In order to turn it into a measure of (sexual) risk aversion, you would at the very least need to ask the students to choose between two (or more) of the options, with different levels of risk and different levels of either 'beneficial payoff' or (more likely) cost.

Perceptions of safety of the different options is one component of the decision of which option to engage in (or to engage in none of them), but alone it does not tell you about risk aversion. A student might report that they believe the options convey a low degree of safety, but that doesn't mean that the student is risk averse. It just means that they believe that the options presented to them are high risk (low safety). Similarly, a student who reports that the options convey a high degree of safety is not necessarily less risk averse than a student who reports that the options convey a low degree of safety.

How would we expect health students to be different from other students? You might expect health students to be better informed about the actual safety associated with the different options (at least, you'd hope that they would learn this in their health studies!). In other words, you might expect other (non-health) students to over- or under-estimate the degree of safety of the different options to a greater extent than health students. Let's say that non-health students are more likely to over-estimate safety. They are more likely to take risks with their sexual health and in terms of unplanned pregnancy than are health students, because the health students are better informed about the real levels of safety of each option. This would manifest in higher measures of 'perception of safety' among non-health students than among health students. And these authors would interpret this as greater risk aversion among health students, when in fact it is entirely driven by the non-health students being misinformed relative to the health students.

Notice also that the measure of 'perceptions of safety' increases if students believe that oral sex is safer (in terms of avoiding risk of STDs), or if kissing is safer, or if vaginal sex is safer, with no consideration of the actual level of risk associated with each option. It would have been better to evaluate some of the options separately, rather than all together, since evaluating them all together really turns their measure into a general measure of 'perceptions of safety of sexual activity'.

That latter problem aside, the results of the paper are still interesting, provided you interpret them (correctly) in terms of 'perceptions of safety of sexual activity'. Students who reported as virgins had lower perceptions of safety (which might explain in part why they are still virgins). Older students had lower perceptions of safety (I guess, you learn from your mistakes, or your friends' mistakes?). Male students had higher perceptions of safety in terms of STDs, but not in terms of unplanned pregnancy (this one was a bit or a surprise, as I would have expected the opposite). Non-religious students (which the authors label as atheists) had lower perceptions of safety in terms of STDs, but higher perceptions of safety in terms of unplanned pregnancy (I guess the religious students are more worried about pregnancy, which can't easily be hidden from their peers and family, than they are about STDs, which can?).

Anyway, even though the results are interesting, it doesn't change the fact that this is not the way to measure risk aversion.