How to Measure Completion Time
How do you measure completion time of a project? There are two primary ways to measure completion time: need dates and cycle time.
Need dates are set by managers, customers or programs. Need dates can be determined from Gantt charts or financial metrics.
Cycle time is a measure of the time it takes from start to finish to complete a task. What are the advantages and disadvantages of these methods of measuring completion time?
Advantages of Using Need Dates
- Need dates are simple to understand. We must be done by date X.This can be the end of the week, of the month, of the quarter or the year. Regardless of other factors, when the time runs out is known.
- Planned start dates and end dates provide instant prioritization of work. Staffers know that they must start on projects with start dates of this day or upcoming days. If the start date isn’t for a week, it can be ignored for a week.
- Resource management can be based upon need dates, such as allotting extra people or paid overtime as a need date approaches.
- Planned start dates and end dates work best on very large projects with diverse tasks, such as construction. When each task is run off Gantt charts and schedules, need dates are a natural way of planning when work must occur.
Disadvantages of Using Need Dates
- Need dates can be assigned arbitrarily or on a whim. While it sets a goal, the goal may not be practical or even possible.
- The date given may not be practical given the average cycle time of all required prerequisite steps. When management bases metrics on meeting the calendar, they risk corners being cut to make the date.
- Need dates pass by regardless of someone’s vacation, medical emergency or unavailability. If the person comes back and finishes quickly the next day after the need date, it is still judged as late, even if the total days worked is at or below the average cycle time.
Advantages of Using Cycle Times
- Cycle time is a value that is easily measured regardless of delays that may have affected the start time.
- Cycle time can be managed as its own metric for each process step. Performance for one skilled group is thus separate from other groups. Drafting can improve their cycle time to create drawings and models regardless of how slow test engineering goes.
- Six sigma projects targeting cycle time reduction can reduce cycle time for critical steps. While a whole process may be too unwieldy or costing to improve, cycle times for commonly performed or lengthy processes can be driven down to the benefit of the whole organization.
Disadvantages of Using Cycle Times
- A single long cycle can drive up an average cycle time.
- Rarely performed processes have an average but very high variability that should give groups measured by cycle time significant leeway. If the process has been completed in 2 days and in 10 days, the average is 6, but you cannot be angry if the third try takes 8 days.
- You’re done when you’re done, regardless of when the customer needs it done.