HOME
TheInfoList



A man-hour or person-hour is the amount of
work Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking * Work (physics), the product of ...
performed by the average worker in one
hour An hour (symbol: h; also abbreviated hr) is a unit of time conventionally reckoned as of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions. There are 60 minutes in an hour, and 24 hours in a day. The hour was ...
. It is used for estimation of the total amount of uninterrupted labor required to perform a task. For example, researching and writing a college paper might require eighty man-hours, while preparing a family banquet from scratch might require ten man-hours. Man-hours exclude the breaks that people generally require from work, e.g. for rest, eating, and other bodily functions. They count only pure labor. Managers count the man-hours and add break time to estimate the amount of time a task will actually take to complete. Thus, while one college course's written paper might require twenty man-hours to carry out, it almost certainly will not get done in twenty consecutive hours. Its progress will be interrupted by work for other courses, meals, sleep, and other human necessities.


Real-world applications

The advantage of the man-hour concept is that it can be used to estimate the impact of staff changes on the amount of time required for a task. This is done by dividing the number of man-hours by the number of workers available. This is, of course, appropriate to certain types of activities. It is of most use when considering 'piece-work', where the activity being managed consists of discrete activities having simple dependencies, and where other factors can be neglected. Therefore, adding another person to a packaging team will increase the output of that team in a predictable manner. In transport industry, this concept is superseded by
passenger-mileThe units of transportation measurement describes the unit of measurement used to measure the quantity and traffic of transportation used in transportation statistics, planning, and their related fields. Transportation quantity The currently popula ...
and
tonne-mileThe units of transportation measurement describes the unit of measurement used to measure the quantity and traffic of transportation used in transportation statistics, planning, and their related fields. Transportation quantity The currently popula ...
for better costing accuracy. In reality, other factors intervene to reduce the simplicity of this model. If some elements of the task have a natural timespan, adding more staff will have a reduced effect: although having two chefs will double the speed of some elements of food preparation, they roast a chicken no faster than one chef. Some tasks also have a natural number of staff associated with them: the time to chop the vegetables will be halved with the addition of the second chef, but the time to carve the chicken will remain the same. Another example is the adage, "Just because a woman can make a baby in nine months, it does not follow that nine women can make a baby in one month." This adage is often cited in systems development to justify the belief that adding more staff to a project does not guarantee it will get done quicker. Another problem with this model, as
Fred Brooks Frederick Phillips "Fred" Brooks Jr. (born April 19, 1931) is an American computer architect, software engineer, and computer scientist, best known for managing the development of IBM's System/360 family of computers and the OS/360 software supp ...
noted, is that organization, training, and co-ordination activities could more than outweigh the potential benefits of adding extra staff to work on a task, especially if considered only over a shorter time period.


Similar units

The similar concept of a man-day, man-week, man-month, or man-year is used on large
project A project (or program) is any undertaking, carried out individually or collaboratively and possibly involving research or design, that is carefully planned (usually by a project team) to achieve a particular aim. An alternative view sees a project ...

project
s. It is the amount of work performed by an average worker during one day, week, month, or year, respectively. The number of hours worked by an individual during a year varies greatly according to
cultural norms Social norms are regarded as collective representations of acceptable group conduct as well as individual perceptions of particular group conduct. They can be viewed as cultural products (including values, customs, and traditions)Sherif, M. (1936 ...
and
economics Economics () is the social science that studies how people interact with value; in particular, the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and ...
. The average annual hours actually worked per person in employment as reported by
OECD The Organisation for Economic Co-operation and Development (OECD; french: Organisation de Coopération et de Développement Économiques, OCDE) is an intergovernmental economic organisation with 37 member countries, founded in 1961 to sti ...
countries in 2007, for example, ranged from a minimum of 1,389 hours (in the
Netherlands The Netherlands ( nl, Nederland ), informally referred to as Holland, is a country primarily located in Western Europe and partly in the Caribbean. It is the largest of four constituent countries of the Kingdom of the Netherlands. In Europe, the ...

Netherlands
) to a maximum of 2,316 hours (in
South Korea South Korea (Korean: /, RR: ''Hanguk''; literally /, RR: ''Namhan'', or /, MR: ''Namchosŏn'' in North Korean usage), officially the Republic of Korea (ROK; Korean: /, RR: ''Daehan Minguk''), is a country in East Asia, constituting the ...
).


Productive system hours

The concept of productive system hours (PSH) has been used in forestry in Austria and by extension to other work. It includes time for breaks and can be used to calculate how long it may take to complete a task, including required recovery times from physically strenuous work, as well as legally required breaks or other human interactions. If it includes 15-minute breaks, it is written as (PSH15). A related concept is productive machine hours (PMH). More details in the paper "Influence of Terrain Conditions and Thinning Regimes on Productivity of a Track-Based Steep Slope Harvester".


See also

*
Henry Gantt Henry Laurence Gantt (; May 20, 1861 – November 23, 1919) was an American mechanical engineer and management consultant who is best known for his work in the development of scientific management. He created the Gantt chart in the 1910s. Gantt ...

Henry Gantt
* Frank Bunker Gilbreth, Sr. *
Labor economics Labour economics seeks to understand the functioning and dynamics of the markets for wage labour. Labour is a commodity that is supplied by labourers in exchange for a wage paid by demanding firms. Because these labourers exist as parts of a so ...
*
Mechanization A water-powered mine hoist used for raising ore. This woodblock is from ''De re metallica'' by George Bauer (pen name Georgius Agricola, ca. 1555) an early mining textbook that contains numerous drawings and descriptions of mining equipment. M ...
*
Productivity Productivity describes various measures of the efficiency of production. Often, a productivity measure is expressed as the ratio of an aggregate output to a single input or an aggregate input used in a production process, i.e. output per unit of ...
*
Scientific management Scientific management is a theory of management that analyzes and synthesizes workflows. Its main objective is improving economic efficiency, especially labor productivity. It was one of the earliest attempts to apply science to the engineering o ...
*
Surplus value In Marxian economics, surplus value is the difference between the amount raised through a sale of a product and the amount it cost to the owner of that product to manufacture it: i.e. the amount raised through sale of the product minus the cost o ...
*''
The Mythical Man-Month ''The Mythical Man-Month: Essays on Software Engineering'' is a book on software engineering and project management by Fred Brooks first published in 1975, with subsequent editions in 1982 and 1995. Its central theme is that "adding manpower to a la ...
'',
Fred Brooks Frederick Phillips "Fred" Brooks Jr. (born April 19, 1931) is an American computer architect, software engineer, and computer scientist, best known for managing the development of IBM's System/360 family of computers and the OS/360 software supp ...

Fred Brooks
' classic book on software engineering *
Time and motion study A time and motion study (or time-motion study) is a business efficiency technique combining the Time Study work of Frederick Winslow Taylor with the Motion Study work of Frank and Lillian Gilbreth (the same couple as is best known through the biogra ...
*
Frederick Winslow Taylor Frederick Winslow Taylor (March 20, 1856 – March 21, 1915) was an American mechanical engineer. He was widely known for his methods to improve industrial efficiency. He was one of the first management consultants. Taylor was one of the intellec ...


References


''The Principles of Scientific Management''
F.W.Taylor, 1911, online
''Shop Management''
F.W.Taylor, 1911, online

online {{refend


External links

Man-years: *Man-year defined as 2000 hours: https://web.archive.org/web/20060722155057/http://www.onr.navy.mil/02/matoc/05_09/solicitations/docs/05-0002-02.pdf (Solicitation Number 05-0002-02: Support Services for the Office of Naval Research for the Legislative Affairs Office (United States Navy Office of Naval Research: Arlington, Virginia, USA, 2004) *Man-year defined as 2087 man-hours

counting 311 "Non-available/Nonproductive" man-hours)
WorkHuman activities ...
Labor {{JEL code, J Work Economy ...
Personnel economics