I come from the Microsoft Project world, where schedules are built using duration and work. However, team members often refer to effort, hours, or my pet peeve “man-days”. What are all of these, and how do they compare?
My nonprofessional definitions are summarized as follows, with examples below:
- Duration – the amount of time it takes to complete a task. Measured in days, from task start to task end. Can also be referred to as calendar time.
- Work – the amount of hours it takes to complete a task. Measured in hours, from task start to task end.
- Effort – the same as work if you’re talking about hours. Technically, effort is a % allocation of your “focus” on a task.
- Hours – the same as work.
- Man-days – the same as work, but expressed in days instead of hours.
To illustrate, we will use a simple example: We need to build a wall.
Example 1: Duration
The wall will take one builder 10 working days to build. In Microsoft Project, this would be represented as follows:
- Duration is 10 days
- Work is 80 hours (Assuming the builder works 8 hours a day, that’s 10 x 8 = 80 hours)
- Effort is 80 hours
- Hours is 80 hours
- Man-days is 10 days. Be careful! Man-days is not the same as duration. See the next example.
Example 2: Man-days
The same wall will take two builders 5 working days to build.
- Duration is 5 days
- Work is still 80 hours (2 builders, each working 8 hours a day for 5 days)
- Effort is 80 hours
- Hours is 80 hours
- Man-days is 10 days
Example 3:
We have two builders, but the client will only allow us to work for 4 hours in the mornings. After that, we need to leave the building site. The same wall will take the two builders 10 working days to build.
- Duration is 10 days
- Work is still 80 hours (2 builders, each working 4 hours a day for 10 days)
- Effort is 80 hours
- Hours is 80 hours
- Man-days is 10 days
In Summary:
When team members start using non-standard terminology, make sure that you understand exactly what they mean. Work is the only reliable source when quoting customers on a time and materials basis, as in the examples above. Work remained at 80 hours regardless of how the work was resourced. Wherever possible, I always refer to Duration and Work. These are two “standards” that most other Microsoft Project users will be familiar with. Leave a comment and let me know if you found this helpful.