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Only 24 hours in the day: academic trade-offs in teaching and research

The above image is of Firestone Library at Princeton University (creative commons license).


How do you spend the majority of your time as a tenured or tenure-track professor in the natural sciences?  That was the question we started to answer using survey data collected here on the blog several weeks ago.  We received responses from 90 people in the PLoS Ecology community, including 72 ecologists and biologists, 11 geologists, 3 physicists, and 4 chemists.  Our sample included people at their current position for less than a year and extended to Endowed Chairs who have been at their position for 36 years.  This week I am going to share overall results for the dataset.  I will post a follow-up next week with finer-resolution results depending on current rank (51 responses were from people at the Assistant Professor level), field, and type of institution.  Also, please note that this is an informal survey.  Participants were not incentivized to participate and participation was not equal for each of the different types of institutions.  Our sample is restricted to the reach of the PLoS Ecology blog and the social networks of each of its authors.


The questions from our survey:


  1. What is your field of study?
  2. What type of institution are you currently employed at?
  3. How long have you been at this position?
  4. What is your current rank?
  5. How many classes or different sections of classes do you teach per semester?
  6. How many unique courses (with separate syllabi) do you teach per semester?
  7. How many total students do you teach per semester?
  8. On average, how many students do you have in each class?
  9. How many hours of in-class time does this entail per week?
  10. What percentage of your classes are undergraduate?
  11. On a scale of 1 to 5, how much is undergraduate mentorship and teaching excellence valued in tenure decisions at your institution?
  12. What percentage of your time during the semester do you devote to research?



We analyzed differences among questions 5-12 depending on type of institution (R1, R2, Master’s granting, Tier 1 liberal arts college, all other liberal arts colleges, Art & Design schools, and Community Colleges).  Based on our survey, professors at R1 institutions teach the fewest classes per semester (mean = 1.5), resulting in 7.7 hours in the classroom per week, to a group of ~60% undergraduates.  In terms of the quality of teaching, responses from participants ranged from, “teaching excellence is not considered at all,” to, “excellence in the classroom is required for tenure,” and the average response was closest to, “teaching excellence is considered a bonus.”  Professors at these schools spend an average of 45% of their time on research (grant writing, advising graduate students, writing manuscripts, analyzing data, setting up new experiments, collecting data, etc).

We analyzed each of the above questions using a simple ANOVA with institutional type as a single factor and each response variable as an independent response. Only the significant relationships are shown above, with letters indicating differences using post-hoc Student's t-tests and error bars representing standard error of the mean.
We analyzed each of the above questions using a simple ANOVA with institutional type (Question 2) as a discrete predictor variable and each question (#5-12 above) as a continuous response variable. Only the significant relationships are shown above, with letters indicating differences using post-hoc Student’s t-tests and error bars representing standard error of the mean.  Full statistical results available below (in Appendix).


At the other end of the spectrum is, arguably, a completely different type of job.  Professors at Community Colleges teach an average of 3.75 classes per semester, totalling 20.5 hours in the classroom per week, to exclusively undergraduates.  On average, teaching quality is heavily emphasized, with most people answering that, “teaching is a significant component of tenure decisions.”  The majority of these professors spend 10% of their time on research.  If each class takes 2-4 hours of prep time per hour of class, the trade-off becomes pretty clear.  On average, these positions might entail 82 hours of prep time per week (grading, writing lectures, reading papers, creating classroom activities) + 20.5 hours of in-class time.  On the high end, we are talking about 102 hours for teaching each week.  It’s hard to imagine where the extra time for research would come from, at least at the beginning of a career when you are creating course content for the first time.


Number of classes taught per semester is inversely related to percentage of time available for research.
Total number of classes taught per semester compared with percentage of time spent on research. Means calculated for each type of institution. Error bars represent standard error of the mean.

All other types of institutions fall somewhere in the middle of this distribution, with the actual ratios between teaching and research varying along a spectrum.  The single best predictor of time for research was simply the total number of classes you teach per semester (above).  This was somewhat surprising to me: these classes can vary by many different types of variables.  You could teach two classes per semester with 15 students each (mixed undergraduates and graduates) or two lecture classes with 200 students in each class.  Those two situations are quite different.  However, having 200 students in your classes also usually comes with an institutional understanding that your investment per student is reduced.  You may have graduate student TA’s helping with grading and less emphasis on teaching evaluations.  The total amount of time spent in those two situations may actually end up being quite similar.  Either way, there is a clear trade-off in the data.  The more classes you teach per semester, the less time you have for research.  I find the general conclusion to be self-evident, but the particulars to be very interesting.  A few things come to mind:


  1. There is an enormous difference between teaching 1.5 classes per semester and teaching 2 classes per semester, at least in terms of actual time for research (or institutional requirements for research).  This is likely a reflection of differences in institutional priorities between schools that expect professors to teach one class per semester (mostly R1 and R2 Universities) compared with all other types of institutions.
  2. There is a lot of overlap between Master’s Granting Universities and all other small liberal arts colleges in terms of research allocation, though importantly this doesn’t really come with a reduction in teaching load.  Professors at all other small liberal arts colleges seem to be teaching an average of 1 class more per year (0.5 classes more per semester), but still spending just as much time on research.  That sounds like a time pinch.
  3. Art & Design schools are incredibly variable in terms of teaching load and time for research.  For these schools the reality of the position is something you would need to verify during the interview process.  Asking how many courses you will be teaching per semester is a good place to start.  You could be at an Art & Design school with the same teaching to research ratio as an elite liberal arts college.  You could also be at an Art & Design school with the same teaching to research ratio as a Community College.
  4. Similarly, within any of these institutional categories, there is quite a bit of variability.  Depending on the particulars of the position, you could be at many different types of schools and fall almost anywhere on this distribution.


One essential rule of thumb based on these data: regardless of how much time an institution says you might have for research, you can probably calculate your actual time available based on how many courses they are asking you to teach per semester.  If they are asking for 3-4 classes per semester and research excellence, you’ll have to ask yourself where that extra time is going to come from.




Appendix: We assessed whether each of the following categories varied depending on type of institution (R1, R2, Master’s granting, Tier 1 small liberal arts college, all other small liberal arts colleges, Art & Design school, Community College).

All statistical results

Read: Only 24 hours in the day PART TWO: Breakdown by type of institution

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