Striking evidence that legalising cannabis negatively affects undergraduates’ behaviour and leads to - in particular, weaker - students failing their exams. has been provided by three new studies. One of these studies is from Olivier Marie, Endowed Professor of Labour Economics at Erasmus School of Economics. He and Ulf Zölitz found that students’ grades at Maastricht University improved when cannabis laws were tightened.
Maastricht, a university city in the far south-east of the Netherlands locked between the German and Belgian border. The city introduced a policy that limited access to its 13 coffee shops based on nationality. Natives, Germans and Belgians were exempted but all other nationals, including those studying in Maastricht, were no longer able to buy cannabis legally. This policy was in place for 7 months after which the cannabis shops went on strike in anticipation of new legislation that, in their eyes, impeded their customers’ privacy. This situation created a perfect natural experiment setting for researchers Olivier Marie and Ulf Zölitz to investigate the causal effects of a change in legal cannabis access on university student performance.
Using data on regular test results over time for all business and economics students, Marie & Zölitz found that the restriction on cannabis access significantly increased performance of individuals from banned nationalities. During the restriction policy, their scores were on average 10.9 percent of a standard deviation higher and their probability of passing a course increased by 5.4 percent. The literature also suggests that cannabis consumption impairs numerical skills proportionally more. In line with this, the effects of restricted access were found to be 3.5 times larger for performance in courses that required statistical and mathematical skills.
These findings could be interpreted as an argument for limiting cannabis access as it does suggest that it changes consumption behaviour of certain individuals who in turn have lower productivity. However, the authors stress that their findings are a small part of a multi-dimensional societal cost and benefit analysis and should not be interpreted in isolation from other perspectives. There might be some severe negative consequences of making access illegal – such as increased demand through illegal channels and thereby routing cash flows into the pockets of narcotic gangs.
In any case, an important takeaway message from this research is that smoking cannabis before a (statistics) exam might not be such a good idea!
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Read the entire article on Daily Mail, d.d. 3 Februari 2019