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Estimations in Project Management

The Way We Think When We Make Estimations

Let’s go back to the original conversation between the programmer and the project manager. How long does it take to say, “I think abo-o-out … five days”? Try to do it. It shouldn’t take longer than four seconds even if you pause before the sentence. Remember, we assume the programmer already understands the scope of the task. He uses these four seconds to make an estimate, here is his mental process: 

1. The programmer recalls the scope of the task. He does this very quickly as he has already thought about it. In his mind, he has already broken the activity into few small subtasks and has analyzed the duration of each subtask separately.

2. The programmer tries to recall similar projects, mostly with comparable scope or similar writing tools. He checks how relevant these projects are to the current task. That gives him an approximate answer, around four- five days. The programmer does this analysis almost instantaneously. In the programmer’s mind, it is not an analysis; it is almost intuitive response based on his memory input. 

3. The programmer spends the rest of these four seconds trying to come up with an acceptable estimate. Too low, he won’t be able to complete his job on time. Too high, the project manager will be unhappy (he is not an idiot and has his own estimate).

When the project manager asks “Are you sure?” the programmer doesn’t repeat his analysis, he is just trying to determine whether his answer has satisfied the manager. Moreover, as you might have noticed, he did not have the time or information to understand any potential pitfalls, which he implicitly acknowledges with the phrase: “…if everything goes well…”.

It is truly amazing how much thinking can be done in only four seconds. It is even more amazing that estimates done this way may be absolutely correct. Intuitive estimations work well when the person who performs the estimation has participated in similar activities many times and remembers his or her experiences very well. However, in research and development projects or, almost all new projects, this is often not possible.

Accurate estimation cannot be done without valid inputs. The information for estimations can only come from two sources:

1. Historical data or data about previous similar projects. This data can be captured in the project manager’s brain or obtained as a result of data analysis.

2. Measurements of the current project’s performance. Analysis of what has already occurred in the project makes is possible to forecast what will happen in the future.

The human brain processes this information extremely fast using certain simplification techniques. In many cases, they work very well, in others they can lead to systemic mistakes or biases. 

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