Most of us know the type: the friend who complains about the horribly long hours he's been pulling at work lately. 

Federal data suggests that friend isn't quite telling the truth.

The New York Times' Catherine Rampell flags this Bureau of Labor Statistics report that explores the gap between how much people think they work and how much they actually work. It finds that, on average, Americans overestimate how much time they spend toiling away in a cubicle by 5 percent to 10 percent.

Those who work the longest hours are prone to the greatest exaggeration, as you can see in this chart below. It maps the gap between estimated work hours and actual work hours (as recorded in a diary) as measured by three separate surveys.

Two surveys here - the red and green lines, above - show some striking disparities for those who think they're pulling the longest days. Turns out, those who claim a 75-hour work week put in only 50 hours at the office. 

It's worth noting that same phenomena occurs when people are asked how much time they spend on other tasks, such as housework. "When asked to provide such daily and weekly estimates," BLS economists John P. Robinson, Steven Martin, Ignace Glorieux and Joeri Minnen write, "survey respondents tend to give estimates that add up to considerably more than the 168 hours," the number of hours in one week.

A few other interesting tidbits from the report: Women are more likely to overestimate their working hours than men as their work week gets longer. You can see that in this graph below, drawn from a Belgium study, which charts the gap between estimated and actual hours worked by gender.

  The gap between perceived and actual work hours looks to have grown over time. In 1965, people overestimated the hours they worked by an average of 1.3 hours for the week. Now, they overestimate by 2.4 hours, on average. Economists think this has to do with the changing nature of the economy. "With the movement of the labor force into more service occupations and other occupations in which work schedules are becoming more irregular (with no time clock to punch as a vivid reminder)," they write, "Workers have fewer benchmarks to use in estimating the number of hours in their workweek."