An important distinction when creating duration estimates is whether the time estimated represents pure work time or gross work time. There is a difference between the two.
Pure work time is 100% uninterrupted work focused on the respective project. Gross work time, however, includes: project related tasks and non-project related activities. Duration estimates will vary significantly depending on whether they are pure work estimates or gross work estimates. So it’s important to clarify if estimates account for pure or gross work time. And it’s your responsibility as the project manager to make sure your project team understands which type of duration estimate to provide: pure or gross.
This article discusses the difference between pure work time and gross work time for work duration estimates.
The work day activities may be divided into three main activity categories: project related tasks, non-project work related tasks, and non-work related activities. The following is a list of activities in each category:
Project Related Tasks
- Project related work
Non-Project Work-Related Tasks
- Logging time for work week
- Answering e-mails and phone calls not related to project
- Company meetings
- Professional Development Training (not related to project)
- Providing technical support for colleagues
- Maintaining computer hardware and installed software
- Backing up computer files
- Organizing files and file cabinets
Non-Work Related Activities
- Private telephone calls
- Checking weather, stocks, and current news.
- Browsing the internet.
- Non-work related conversation
- Visits to kitchenette for coffee, tea, and/or snacks
- Visiting the washroom
- Sick leave
- Employee luncheons
Gross work time includes all the listed items, and pure work time includes only the project related tasks. Some companies estimate that only 70% of gross work time is expended on the actual project. This value may differ among companies. But not identifying estimates as pure or gross worktime is a mistake. And not considering gross worktime invariably results in overly optimistic schedules, which will always be late.
You will also need to additionally note the availability of each resource to work on your project, considering other projects, additional administrative duties, and vacation time. And a resource devoted to one project is more focused and productive than a resource assigned to multiple projects. An over-allocated resource is a problem; project plan objectives cannot be achieved in the real world when resources are over-allocated.
Important duration estimate considerations are as follows:
- Estimates are properly identified: pure or gross.
- Estimates are consistently either pure or gross work time.
- Estimators understand your company’s definition of pure and gross work time.
- Timesheet actual hours reflect respective pure or gross duration estimates on the project schedule. This supports one-to-one comparison of project estimates to actual hours charged.
- Consider project cost computations. Are they based on pure work time or gross work time? Typically client labor cost estimates include personal time. Pure work estimates therefore may need to include a multiplication factor to adjust for overhead work costs.
Summary
It is important to make duration estimates all pure work time or all gross work time; mixing the two breeds confusion. Make certain pure and gross working times are understood. Consistently fill in timesheets with the type of pure or gross estimates collected. This supports comparing actual hours and estimated hours. Pure worktime workweeks are less than 40-hours. As most employees want to charge a 40-hour labor workweek, almost all organizations with timesheets use gross work time estimates.