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New time unit needed!

We need a time unit that’s bigger than a minute but smaller than an hour.

I thought of it when writing this comment in which I referred to “2100 valuable minutes of classroom time” during the semester (that’s 75 minutes per class, twice a week, for 14 weeks).

A minute of class time is pretty useless. You can’t do much in a minute. Or, you can do a bit in a minute, but not much, and it will take another minute to organize it and another to recover. So, for the purposes of teaching, or working, a minute is not a good unit of time.

But an hour is too long. I could refer to “35 valuable hours of classroom time” but that would be misleading, as you can do lots of stuff in an hour. Time really drags if nothing much is going on.

So . . . a minute is too short, an hour is too long. We need a new unit. 5 minutes, maybe? Then a 75-minute class is 15 intervals long. That’s about right. I can do 15 little things in 75 minutes. An interval of 5 minutes is pretty much the smallest indivisible unit of time.

Or maybe the interval should be 10 minutes? Then we’d be talking a lot about half-intervals but maybe that’s ok.

The name “interval” is no good, though. What should we call it?

So here we go

OK, we have 2 decisions to make:

First, what should be the length of our new time unit? I’m liking 5 minutes but I can see the argument for 10.

Second, what should it be called?

Once we’re settled on both these things, we’re good to go.


  1. Radford Neal says:

    Something around 10 minutes seems good to me. Which is fortunate, because that’s almost exactly a what a milliweek is!

  2. Zach Kurtz says:

    It’s a Gelmate, and it’s defined as how long it takes for Andrew Gelman to say one thing.

  3. Xi'an says:

    Good point, Radford. But then a microyear is about 5 minutes and it can be argued that a year is more of an absolute unit than a week that is a purely human or administrative division.

  4. Anonymous says:

    You don’t need a new unit. Just change the base of the counting system. People have been complaining about the problems with using decimal (greed, war, pollution) for awhile. This proposal for duodecimal seems to meet your requirement for a ~75 minute unit:

    “Dozenal (a) will call for a clock that has 72 divisions. The day will still be 24 hours, but each hour will have 72 minutes, and each minute 72 seconds. What does this mean for you? Hours will still be the same and time keeping will not be constructively different than it is now. The only major difference is that the minute and the second will be slightly shorter than what we’re used to (1 dozenal (a) minute = 50 standard seconds and 1 dozenal (a) second = 25/36 standard seconds).”

  5. Robert Kern says:

    15 minutes is the minimum billable time increment in most industries that track such things.

  6. Rahul says:

    Tag: First World Problems.

  7. Dan says:

    It seems like nature stuck us with days, months, and years, but are we going to get rid of the others? How did minutes, hours, and seconds start? If we are just getting rid of hours, since I think we all agree they aren’t fun, should we consider how many of our new unit fits in a day? If we stick with minutes and want a number that seems “roundish” for units/day, 4,6,8,9,12 seem good.

    • Radford Neal says:

      Perhaps Xi’an could comment further, but I think the French tried the decimal version of such ideas back about 100 million minutes ago…

      By the way, a microyear is approximately half a minute, not five minutes, so I’m still for milliweeks.

    • Nick Cox says:

      Months are overrated if your activities don’t really depend on the tides or whether there is a good moon to give more light at night. However, it is arguable — in a largely statistical forum — that in some fields, months are about right statistically because accumulating and averaging about 30 days’ worth of measurements allow you to downplay fluctuations that are often minor. So, in fields ranging from economics to climatology many data series are collected, or at least reported, monthly. Then some fraction of analysis is devoted to compensating for time units that are otherwise awkward and arbitrary.

      • zbicyclist says:

        Sales tracking typically uses quadweeks — 13 four week periods. Each period is the same length.

        But some companies prefer units of 12 (easily divisible into 2 halves and 4 quarters), which results in 4-4-5 type quarters. It’s very advantageous to have hierarchical units.

  8. Harold Brooks says:

    10-15 minutes is fine. I call it “power nap.”

  9. jg says:

    in dutch we’ve got ‘kwartier’ meaning ’15 minutes’.
    (and ‘driekwartier’ makes ’45 minutes’)

  10. jim says:

    For physiological reasons (i.e., carbohydrate metabolism), I say the unit should be in the range of 6-8 minutes.

  11. Clyde Schechter says:

    Well, to me 10 minutes feels a little short as a unit of teaching time. I tend to think of my classes and talks as coming in units of around 15 minutes. Maybe that’s just because I’m verbose? Anyway, 14.4 minutes would be 1 centiday–which is what I nominate. But “centiday” sounds really awful, doesn’t it. Hmm…

  12. Anonymous says:

    9.424778 minutes called a “concentration”. It represents the length of time smart people can concentrate on statistician’s prattle. You can also call it “threepie” since it’s equal to 3*pi.

  13. Anonymous says:

    Pomodoros – 25 minutes.

  14. Real statisticians measure time in microlives.

  15. Jonathan (another one) says:

    In my work, five minute periods are often called “intervals.” Unfortunately, that’s the unit you don’t want to use. Another possibility is six minute intervals, which you call dec-hours. (That’s a hard c, so its pronounced “deck hours.”)

  16. dab says:

    I like microdecade for a time span of about 5 minutes which then makes a 50 minute class almost a microcentury and an eight hour work day nearly a micromillennium….

  17. Emre says:

    Nowadays I work for 25 minutes and give a break for 5 minutes. In the past I did similar routines like 7*4+7. I can say that 5 minutes is a good denominator.

    I use 10, 100, 1000 days as larger units of time calling them (Farsi) dehrooz, sadrooz, hezarrooz but metric system for smaller units is simply impractical.

    For the name I can offer _pentam_. My work would consist of 5 pentams and your 2100 minutes of class would be 420 pentams.

  18. Andy says:

    I really don’t see what’s wrong with “35 hours” in this scenario. Everybody can easily see that 35 hours is indeed a valuable amount of time.

  19. David says:

    My old firm used to bill in 6 minute increments, which has several useful properties: there are 10 such intervals in an hour, and it’s long enough to do something useful like draft an e-mail or review a small segment of code, but not so long that you’re left in a lurch when you, say, dig your way out of your inbox in the morning by sending several different emails on several different client matters.

  20. jonathan says:

    You could convert to a log scale and confuse everyone.

  21. Kevin Dick says:

    Clearly, it should be 8 minutes for the binary tribe. 10 types of people in the world and all that.

  22. elizabeth says:

    6 minutes. call it a “tenth”

  23. Barry R says:

    The French had a go at chopping the day up differently back when they were chopping up aristocrats. Would any of their unit systems work? for examples.


  24. Anon says:


    It is the standard unit for most astronomical observations.

  25. Scott says:

    How about the pipe, a unit popularized by Arthur Conan Doyle, and equal to 16 and two-thirds minutes.

  26. Eric Tassone says:

    +1 to six minutes. It’s 0.1 of an hour, divisible by 2 and 3 (if needed to be subdivided), and, as noted above, the billable unit in some industries (my old law firm billed that way.) And there’s a Doug E Fresh & Slick Rick reference near by….

  27. Dan s says:

    A quinute or quint for short.

  28. Kevin S. Van Horn says:

    I’ve always thought a kilosecond (just under 17 minutes) would be a useful unit of time.

  29. Øystein says:

    In my son’s school, they organize classes into 12-minute blocs, supposedly based on research about the attention span of young kids. Might be suitable also for adults, and “dozen” is a well-established word with long traditions.

  30. 4.8 minutes is 1% of an 8 hour workday. I vote for the centiworkday, now to add it to my GNU units config file…

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