When talking about estimations ysing Agile techniques, there are certain things that are hard to accept for those who, for a few years, have already been planning and calculating times and dates.
We can find many planning techniques Agile: Planning Poker, clothing sizes ( S , M , L , XL , etc. . ) or the Team Estimation Game but, admittedly, all of them are difficult to integrate into a traditional development environment and even less for the customers of our products (at least those I’ve been working with)
Most of us are not used to see a team ‘playing cards’ for a session of Planning poker (at least I’m not) However, I agree with the philosophy behind these techniques and I think the fact that they are becoming increasingly popular it is, in part, because they are attempting to banish certain beliefs about the estimates:
Can we get it right? Estimate is to make a prediction about what would take to do a task or the materials we need to do a job. When we estimate with a high uncertainty, as when we do it based on some procurement specifications, rather than a prediction is a gamble.
It is obvious that we need to estimate. We try to predict what will happen to make decisions, but unless you have done the same task many times before and we have done it with the same team and under the same circumstances, we must know that there are high chances of being wrong.
The more effort you devote to the estimate we approach reality
To estimate has a cost and a it is a high cost. When we do not know the detail of every feature of the work, Does it make sense to devote hours and hours to elucidate tasks that do not know well? Make an exercise for me, when you finish your next project check the time recorded in each task. You will see that where you estimated 20 took 100 to you and where you estimated 100 hopefully only took 20 to complete the task. You will also see other tasks with no imputed hours. Simply they were not needed. However, how many hours were logged on tasks, which nobody thought about them at the initial estimation.
With this or that technique will estimate better
There are many estimation techniques but few will be as useful as a simple comparison of the time that took to do similar projects, the simple breakdown into smaller tasks or the expert judgment.
To use complex estimation techniques can give us a false sense of security about our estimation but it may not provide much higher reliability .However it can lead us to incur a very high cost (see above) and to invest a precious time that we could have used better in other things (such as reducing uncertainty)