1hr. 30min.
A3.KCI-2. Determine the necessary effort and duration
There is a difference between work and duration. When, for example, the bricklaying activity for a wall is 8 hours work, we can then achieve a duration of four hours by putting two bricklayers on the work.
Estimating the work presents us with a problem. Preferably, you would like to ask the people who will be carrying out the activities for an estimate. Because they are often afraid of making a commitment to it, most people are wary of stating a duration. This fear is, of course, somewhat justifiable. Because they "hang themselves" by guessing their own deadline.
When drawing up the schedule, you should therefore always ask about the amount of work involved and not about a deadline. People have a tendency to include contingency in their estimates in order to accommodate potential setbacks. The best thing is to make a so-called three-point estimate, by asking the experts to give you a pessimistic, an optimistic, and a most-likely estimate. The weighted average is then included in the schedule. By starting with the most pessimistic estimate, you indicate that you are prepared to take possible setbacks into account. The time that you ultimately make available has to be challenging, because when a schedule is insufficiently ambitious, people will work less hard and waste costly time. Quote from Cyril Northcote Parkinson [1] (1909-1992): “Work expands so as to fill the time available for its completion”. This is Parkinson’s law.
Often during the planning stage, the people are not yet available, and you then have to make an “average” estimate. If you have experience in doing this, you can probably do it yourself, but if not, you need expert help. The risk exists that such an estimate is too optimistic, because you tend to estimate someone else’s work more optimistically than when you have to carry it out yourself. Furthermore, it is questionable as to whether you get those people in your team, who you had in your mind during the estimate. Once the staff have eventually been allocated, you have to re-visit your estimates. Are the team members more or less experienced than those you had in mind when you produced the schedule?
Related topic: "3. Estimation methods" on page 201.
Application
You can convert the above into actions on the project/programme/portfolio for which you are currently responsible, by carrying out the following steps:
Determine the actual effort.
Identify which resources you need.
Make a choice as to who you are going to request.
[1] (1957) Cyril Northcote Parkinson, Parkinson’s Law
https://www.knowledgehut.com/tutorials/project-management/pert-estimation-technique
