How important are the standardised tests (such as the TSA) in the admissions process, and if I don’t score well does that mean that I won’t get in?
Good question. Firstly, I think it’s important to keep in mind that Oxford will judge your application holistically - past and predicted grades, a teacher’s reference, your personal statement and even personal circumstance come into play when tutors make decisions, and of course your performance in the interviews are pivotal.
As for the tests themselves, I would say that the tests are often used to eliminate weaker candidates, but the emphasis placed on results varies across degrees. For example, PPE tutors are likely to pay a lot of attention to a student’s score on the TSA (the Thinking Skills Assessment) as it has been proven to have a strong correlation with a student’s ability to get a high grade in their final university exams - stronger even than a student’s high-school grades or ‘prelims’ (first-year university exams) results! However (though this is strictly anecdotal) I have heard that tutors from other degrees (such as my own, English literature) have paid little attention to scores when making their decisions, so long as the score hasn’t been atrocious.
I’d also add that standardised tests are often used by the tutors for STEM subjects to eliminate weaker candidates prior to interviews. For example, engineering students will be invited for interview only if they have scored above a certain amount in the PAT (the Physics Aptitude Test).
Generally speaking, the test scores of successful candidates are at least above the average score for the tests taken in their year of applying. However, it is not unheard of for someone to achieve an average score on their test and still be offered a place - I know a Maths and Philosophy student whose MAT score was perfectly on the mean for the test results in the year he applied, and he was still offered a place.
Overall, I would say across that board that admissions tutors place more emphasis on a student’s performance in an interview, and while test scores help to set you apart as a candidate, not every applicant need have a near-perfect score in order to be successful in gaining a place.