Oxford and Cambridge are collegiate universities. This means that there is no central university, and if you’re studying at Oxbridge as an undergraduate then you’ll be studying at a college. A college is where you’ll eat and sleep so basically where you live, and it won’t affect your studies because you’ll go to the same lectures and labs as people from other colleges. Some of your classes, called supervisions at Cambridge and tutorials at Oxford, are organised by a tutor at your college but other than that your college won’t affect your degree.

As part of your application to Oxbridge you have to choose a college, and this college will interview you (if they decide to give you an interview). If you can’t choose a college, then you can choose to do an open application and this means that you’ll be allocated a college. From 2017 to 2019, approximately one in eight students who applied to Cambridge did an open application, and the figure is similar for Oxford. The allocation is not truly random because it works to even out the distribution of applicants across different colleges, which makes sense given that some courses at some colleges might be undersubscribed or oversubscribed. However, one unfortunate consequence is that if you do an open application, you’re more likely to be allocated to a poorer college.

This is an inevitable consequence of richer colleges being oversubscribed. There is a correlation between college wealth and how many students directly apply to that college, though whether there is causation is something that I can’t prove. If richer colleges are oversubscribed, poorer colleges are undersubscribed, meaning that students who do an open application are more likely to be allocated to poorer colleges.

I did some stats to back this up.

I looked at how many direct applications each undergraduate college at Cambridge received in 2018 and 2019 and plotted it against college wealth. The measure of college wealth is net assets per student, because that is adjusted for the number of students at each college. All sources are at the end of this article.

The correlation is statistically significant.

I looked at how many open applications each undergraduate Cambridge college received in 2018 and 2019 combined and compared it to wealth estimates of each college from 2019.

Even without any statistical analysis, there does appear to be a relationship. The poorer colleges seem to get more open applications.

To ensure that there is in fact a relationship, I calculated Spearman’s rank correlation coefficient, which tells you whether there is a statistically significant relationship between the rankings of two values. This is a nonparametric test, meaning that it uses rankings and not absolute values like Pearson correlation coefficient, and this is appropriate here because the data is not normally distributed.

The Spearman’s rank correlation coefficient (rho) for the data for the open applications is -0.56, which corresponds to a p-value of 0.0017. This is statistically very significant, but not surprising.

The richer colleges tend to be oversubscribed because there tend to be many benefits to being at a rich college, and they’re often more famous and more popular. Generous grants, cheaper accommodation, and cheaper food so it makes sense to apply to a rich college. Therefore, poorer colleges tend to be more undersubscribed and therefore end up with more open applications.

In short, don’t do an open application but choose a college. Although I only looked at data for two years at Cambridge (Oxford doesn’t release this data publicly), it is likely that this pattern will hold true in every year at both Oxford and Cambridge.

If you want help choosing a college, I’ve made a video on that and I’ve made a flowchart for choosing a college at Cambridge.

Sources:

Cambridge’s information regarding open application: https://www.undergraduate.study.cam.ac.uk/applying/ucas-application/making-open-application

Cambridge application statistics: https://www.undergraduate.study.cam.ac.uk/apply/statistics

Wealth of Cambridge colleges: https://en.wikipedia.org/wiki/Colleges_of_the_University_of_Cambridge