The authors use a specific non-market valuation technique that is called discrete choice modelling (which my colleague Riccardo Scarpa is a world-leading expert in, and which I have also been involved in for a couple of projects, including this one). Discrete choice modelling involves presenting the survey participants (in this case, 90 humanities and science students from three UK universities) with a number of hypothetical choices. Each choice involves a number of goods with different attributes (in this case, the attributes included the price of the essay, the quality of the essay in terms of the grade it would receive, the risk of being caught, and the penalty if caught), and often there is also the choice to buy nothing at all. The participants make several choices, which allows us to determine the implicit weighting the participants place on the different values of the attributes.
In analysing the data, Rigby et al. use a latent class model. I won't go into the detail underlying this, but essentially it determines how many different types of decision-makers there are, with each type placing different weight on the attributes of the good (in this case, essays). They found that there were two types of students, corresponding to students who were very reluctant to buy essays, and those who were more willing to do so. They also found that:
...half of our subjects indicate a willingness to buy one or more essays in the hypothetical essay choice experiment. Students’ stated willingness to participate in the essay market, and their implicit valuation of purchased essays, vary with the characteristics of student and institutional environment. Risk preferring students, those for whom English as an additional language, and those expecting a lower grade are willing to pay more. Purchase likelihoods and essay valuations decline as the probability of cheats being detected, and the penalties if caught, increase.There's probably nothing too surprising there. However, why is cheating through buying essays a problem? Because it reduces the signalling value of education. As I wrote in this 2014 post:
One of the key characteristics of a degree or diploma is the signal that it provides to prospective employers about the quality of the applicant for positions they have available. Employers don't know up front whether any particular applicant is good (intelligent, hard working, etc.) or not - there is asymmetric information, since each applicant knows their own quality. One way to overcome this problem is for the applicant to credibly reveal their quality to the prospective employer - that is, to provide a signal of their quality. In order for a signal to be effective, it must be costly (otherwise everyone, even those who are lower quality applicants, would provide the signal), and it must be more costly for the lower quality applicants. Qualifications (degrees, diplomas, etc.) provide an effective signal (costly, and more costly for lower quality applicants who may have to sit papers multiple times in order to pass, or work much harder in order to pass).In the same way that qualifications are a signal, the grade students receive is also a signal of their quality, because it is harder (more costly, in terms of effort) to get an A grade than a C grade. However, if some students are cheating, then high grades are no longer as effective a signal to employers of students' quality. This is because it is no longer more costly for low-quality students to get an A grade, because any student can do so by buying an essay. This reduces the value of education for everyone.
The overall conclusion by Rigby et al. was, unsurprisingly, that if penalties are high enough, students will avoid buying essays. So, universities should be vigilant, and heavily penalise students who are caught cheating. That reduces the expected net benefit of cheating, and reduces the incentive to buy essays. Gary Becker would be proud.
However, an alternative is to make asymmetric information work for you. Most of the online markets where students buy essays simply link up a willing buyer with a willing essay-writer. The sites themselves mostly don't employ people to write essays directly (and those that do are pretty low quality). So, universities could combat this by flooding the online markets with low-quality rubbish essays. How would this work to reduce cheating?
Students can't be sure about the quality of any essay they buy. Essay writers can't easily prove to students that they will write a high-quality essay. So, there is asymmetric information, but is there adverse selection? I argue yes, since sellers of low-quality essays can take advantage of students' inability to distinguish between low- and high-quality essays.
Will the market fail? Students' willingness-to-pay for an essay is affected by the quality of the essay they expect (as per Rigby et al.'s results above). So, if universities flood the market with lots of low-quality rubbish essays, then students will start to expect lower quality essays and adjust their willingness-to-pay downwards, and may drop out of the market entirely (why bother trying to buy an essay if the quality is highly likely to be rubbish). Sites selling essays will make less money and begin to shut down, since they can't easily prove to students that their essays are high-quality. It probably won't make the market fail completely, [*] but it would reduce the problem and be extremely funny (and no doubt distressing for cheating students).
[*] Readers of a certain vintage will remember the music sharing service Napster. In the last months before Napster was shut down, the music companies (I assume - who else would do this?) started flooding the service with fake MP3 files. This didn't work in terms of shutting Napster down, but it was pretty frustrating for users.