Work Hour Skepticism

In the comments John Maxwell links again to a presentation claiming that folks who work more than about 40 hours a week don’t actually produce more:

Working more than 40 hours a week leads to decreased productivity. … >60 hour work week gives a small productivity book. The boost last 3 to 4 weeks and then turns negative. … Ford … [ran] dozens of experiments. As a result … he and his fellow industrialists lobbied Congress to pass 40 hour a week labor laws. Not because he was nice. He wanted to make the most money possible. … Performance for knowledge workers declines after 35 hours, not 40. … Past this they start becoming tired and making dumb decisions. (more)

The claim that Ford needed regulation to get his workers to work only 40 hours is clearly wrong. But the other claims are intriguing, and appeal to my contrarian tastes. These claims were also historically important:

During the first decades of the twentieth century, … a new cadre of social scientists began to offer evidence that long hours produced health-threatening, productivity-reducing fatigue. This line of reasoning, advanced in the court brief of Louis Brandeis and Josephine Goldmark, was crucial in the Supreme Court’s decision to support state regulation of women’s hours in Muller vs. Oregon. Goldmark’s book, Fatigue and Efficiency (1912) was a landmark. In addition, data relating to hours and output among British and American war workers during World War I helped convince some that long hours could be counterproductive. (more)

Now, the most productive people I know, including self-employed folks and those with a huge personal stake in their own productivity, tend to work tons of hours. Either these claims are just wrong about such folks, or they are right on average but don’t apply to the most productive folks, or these folks and their associaties consistently make a huge mistake (as did most of the working world before 1920). Which is it?

The presentation above cites this, which cites this, which cites books from 1894, 1908, 1909, 1913, 1926, and says:

I have found many studies, conducted by businesses, universities, industry associations and the military, that support the basic notion that, for most people, eight hours a day, five days per week, is the best sustainable long-term balance point between output and exhaustion. Throughout the 30s, 40s, and 50s, these studies were apparently conducted by the hundreds; and by the 1960s, the benefits of the 40-hour week were accepted almost beyond question in corporate America. In 1962, the Chamber of Commerce even published a pamphlet extolling the productivity gains of reduced hours. But, somehow, Silicon Valley didn’t get the memo. .. Five-day weeks of eight-hour days maximize long-term output in every industry that has been studied over the past century.

This article quotes a 1980 article “Scheduled Overtime Effect on Construction Projects” as saying:

Where a work schedule of 60 or more hours per week is continued longer than about two months, the cumulative effect of decreased productivity will cause a delay in the completion date beyond that which could have been realized with the same crew size on a 40-hour week.

I couldn’t find that source, but I found a 2001 review article:

Based on the foregoing overview of available studies it is evident that only a few are based on original data. Moreover, less than reliable data have been published and republished over and over giving a false appearance of originality. Finally, data are available for a limited number of trades only. Figure 16 compares the reported efficiency from various studies for the 50-hour, 60-hour and 70-hour work weeks with the majority based on 10-hour workdays and an overtime schedule of four consecutive weeks. (more)

That figure 16 estimates a max total productivity over four weeks at 60 hours per week. But the study it cites that looked longest, found that by sixteen weeks median per hour productivity had fallen by 30%, 50% and 62% for 50, 60, and 84 hour work weeks. (Though for that source “The origin of the data and the work environment are unknown.”) So yes, the basic claims above do weakly check out, at least for the construction industry. But basic questions still remain: How solid is the data here, does this apply to all industries, and does it apply to our most productive workers?

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  • Peter Twieg

    I’d also question whether increased labor opportunity over times allows for people to sort into organizational cultures whose schedules they find more amenable: Even if the [i]average[/i] worker’s marginal productivity is negative after 40 hours of work, this doesn’t mean that [i]no[/i] workers should put in more than 40 hours, and we’d expect to see employees who are capable of working productively past 40 hours to be the ones in the 40+-hour jobs. I imagine that this kind of matching is being done much more effectively in 2011 than in it was in 1911.

  • mattw

    It must depend on the nature of the work. If I produce widgets at a rate of 10 per hour for the first 40 hours in a week, and for the next 20 hours in the same week my productivity drops to 7 Widgets per hour, I’m still getting much more work done by increasing my hours worked regardless of the productivity drop.

    • Someone from the other side

      Yes but if your spot in the assembly line binds a huge amount of capital, it may be more effective to pay another guy to produce 10 widgets per hour and send you home…

  • Perry

    When I’ve worked very long hours, it was typically in a management capacity, and my decision making and ability to attend meetings, although clearly impaired by 14 hour days, was not so impaired as to make an 8 hour day better for my startup. I had people working Australia, California, the US East coast and Europe, and I simply had to communicate with them all regularly, which lead to very long hours.

    If I’d been trying to write software that many hours a day I’d have been useless, but coordinating and sales type activities were possible even when a bit on the tired side.

  • http://www.andreasmoser.wordpress.com Andreas Moser

    Life is more than just work.

  • http://webtrough.wordpress.com DW

    So there’s a distribution of optimal work-week length for any individual depending on task and motivation, then. And the mean is 35-40 hours.

    Doesn’t seem too crazy to me.

  • Michael Vassar

    My guess is that most of these studies are using the word ‘work’ to mean simple repetitive tasks done at the behest of an employer, not ‘any productive activity’. Certainly traditional farming communities gravitate towards much higher levels of work during high work periods because they have discovered empirically that the people who work less get worse returns.

  • WL

    I think its worth noting that a lot of the high productivity workers that do routinely hammer out 60 hours a week or more often take a rest when they need it. When I worked as a consultant, my company more-or-less insisted I use some vacation days every 4 or 5 weeks to fight burn out.

    I worked long hours for a startup, but in time periods where we knew sales would be weak we would shut down for weeks at a time. I think productivity losses are more problematic for shift workers with no vacation time.

  • Anonymous age 69

    I worked in a high tech factory for 31 years. Management at times had literature we could read. Studies of repetitive work, such as simple assembly line work, did in fact drop in total weekly output after around 40 hours. Not hourly production, but total weekly output went down as hours went up.

    Those robber barons did not guess when they allowed their workers to work only 40 hours a week.

    We had hot projects that would go on very long hours. They were noted for mostly surviving and hanging out for 60 or 70 hours a week, and did not get more done. We viewed overtime as “gravy train.”

    • http://hanson.gmu.edu Robin Hanson

      Have any citations?

  • Pingback: Overcoming Bias : Construction Peaks At 60Hr/Wk

  • https://plus.google.com/106597887376283858570/posts Kaj Sotala

    The 1991 paper The Role of Deliberate Practice in the Acquisition of Expert Performance ( http://graphics8.nytimes.com/images/blogs/freakonomics/pdf/DeliberatePractice%28PsychologicalReview%29.pdf ) seems possibly relevant for what you’re looking after:

    “Early in this century, considerable research was directed toward the subjective experience of mental fatigue and its consequences for performance. On the one hand, efforts to demonstrate decline in performance, even after consecutive days of mental multiplication for 12 hr per day, have been remarkably unsuccessful (Arai, 1912; Huxtable, White, & McCartor, 1946). On the other hand, the subjective feelings of discomfort and aversion often become so strong that continuing these experiments beyond 4 days would seem very difficult, if not impossible. The best data on sustained intellectual activity comes from financially independent authors. While completing a novel famous authors tend to write only for 4 hr during the morning, leaving the rest of the day for rest and recuperation (Cowley, 1959; Plimpton, 1977). Hence successful authors, who can control their work habits and are motivated to optimize their productivity, limit their most important intellectual activity to a fixed daily amount when working on projects requiring long periods of time to complete. […]”

    “Kaminski et al. (1984) found that young elite performers in music and various types of sports, such as gymnastics, swimming, and ice-skating, spent more than 15 hr on weekly practice. Furthermore, this amount did not differ systematically across domains. When expert performers make a full-time commitment to the domain, our studies showed that they spend between 50 and 60 hr per week on domain-related activities. Less than half of that time (about 25 hr per week) is spent on deliberate practice, and this time is distributed across the entire week in practice sessions of limited duration. Our analyses of rest and relaxation were consistent with our claim that these individuals had attained a level of deliberate practice limited not by available time but by available resources for effortful practice. […]”

    “Consistent with the data on athletes and musicians, eminent scientists are completely absorbed in their vocation so “as to seriously limit all other activity” (Roe, 1953, p. 49). The degree of commitment has been quantified in a couple of sources (Bruner, 1983; J. R. Hayes, 1981) to suggest that scientists must work 80 hr per week for an extended time to have a chance of reaching an international level in their field […]”

    “Many scientists involved in laboratory studies, teaching, and administration must cope with external constraints on their time that may partially determine how they schedule writing and thinking. In this regard, it is particularly interesting to examine the way in which famous authors allocate their time. These authors often retreat when they are ready to write a book and make writing their sole purpose. Almost without exception, they tend to schedule 3-4 hr of writing every morning and to spend the rest of the day on walking, correspondence, napping, and other less demanding activities (Cowley, 1959; Plimpton, 1977). […]”

    “Across several different types of domains, elite performers are found to engage in similarly high levels of selected activities, such as deliberate practice. The complete focus on the domain provides most of these individuals with much available time, yet the time for deliberate practice occupies only a fraction of that time, with clear preferences about the best time of day. The amount of time they spend on practice and other highly relevant activities appears to be limited by how long the demanding activity can be continued with sustained benefits rather than by the available time.”

    Also a paper I ran across while hunting down for that one, http://www.tau.ac.il/~ashirom/pdf/123.pdf , surveys some evidence for long work hours being correlated with health problems, which may be relevant if looking for long-term effects. E.g.:

    “Barton & Folkard (1993) investigated the effects of shiftwork on health. They found shiftworkers working, on average, 48 hours or more a week suffered greater mental and physical health problems (e.g. anxiety, cardiovascular problems, digestive problems and neuroticism) than those who worked fewer hours. Buell & Breslow (1960) found a significant relationship between the number of hours worked and mortality from cornonary heart disease (CHD). Working more than 48 hours per week doubled one’s chances of dying from CHD. These findings were based on United States census information over a three-year period, with a sample size of 22 176.”

    • http://hanson.gmu.edu Robin Hanson

      A good find – thanks!

  • Simone Simonini

    Many consultants bill by the hour. My employers make much more money if I am less productive off of long-hour fatigue, up until the point it starts costing them business.

  • http://asymptosis.com Steve Roth

    “Now, the most productive people I know, including self-employed folks and those with a huge personal stake in their own productivity, tend to work tons of hours. ”

    Substitution error? The question asked is “who’s more productive per hour.” Tough to calculate//estimate, so the brain answers a different question: “who produces the largest quantity?”