Every admissions season, many students applying to statistics and biostatistics programs are intimidated by the task of writing personal or research statements. Indeed, there is an entire sub-forum on GC dedicated to SoPs (Statements of Purpose) where there is much hand-wringing over how to craft the perfect text.
But while I can't speak for disciplines outside of the statistical sciences, I can confidently say that in stat and biostat, the evidence strongly suggests that personal statements have little impact on admissions.
I've written several posts about this in the past; here's a summary of why you should stop worrying so much about a 1-2 page essay:
1. Mathematical ability is best assessed through academic records and test scores (and to a lesser extent, letters), so it is generally quite easy to order students on this important trait.The pool of students applying to statistics and biostatistics departments isn't particularly deep, so that a major concern of even excellent departments is whether applicants can handle the requisite mathematical coursework and exams.
2. Very, very few applicants have meaningful statistical research experience before starting graduate school. As a result, many students end up working on dissertations in areas entirely different than they were initially interested in... and this is totally OK!
3. Funding in most (but not all) U.S. stat/biostat programs is allocated at the department level to the strongest incoming students, so applicants aren't typically "matched" to potential advisors who agree to fund them*. Rather, the department projects the total number of positions available and then tries to recruit up to that number of students. Once the students are on campus, they are then either assigned to a position or (ideally) have some choices available to them.
Given points 2 and 3, declarations in the personal statement such as "I am very interested in studying [X] with Professors [u,V,W]" usually carry little weight. They typically translate to: "[X] is a hot topic which I know very little about but sounds interesting, and I see on your website that Professors [u,V,W] list [X] as a research area." Which, again, is JUST FINE, since that's essentially all most people can credibly write.
4. Research potential *is* important, but the best source of information on this trait is letters of recommendation, not a one-page essay. In some fields, part of showing research potential is demonstrating that you have already thought of a reasonable project that will turn into a dissertation. Since (virtually) no one applying to stat/biostat has a "shovel-ready" dissertation idea, research potential is generally assessed using some combination of mathematical ability, creativity, and perhaps some exposure to lower-level research, all of which are best evaluated using other parts of the application.
I don't mean to denigrate the personal statement too much. There are a few key things to avoid (eg. rampant grammatical errors, aimless rambling, saying you have no intention of pursuing an academic career if you are applying to a PhD program) and of course there will be exceptions to every rule, but in general, as long as the PS is competent it probably won't affect your chances of admission significantly.
As an addendum, the one main exception to the "personal statements aren't important" rule is applicants who have an unusual academic record/background compared to the typical stat/biostat grad applicant. This could include, for example:
- Applicants who have been out of school for several (5+) years.
- Applicants who are changing fields.
- Applicants who lack prerequisites.
- Applicants whose academic performance was affected by serious personal/medical circumstances (e.g., one semester of terrible grades due to death of parent, major illness, etc.)
If you fall into one of the first three categories, we want to know why you chose statistics/biostatistics and how you think your background has prepared you for success in grad school. If the last category applies, it's important for us to know since it provides needed context for interpreting your previous academic performance.
