Why you should do estimation in groups

More than any other activity, estimation of size or effort it will take to build a digital product is based on individuals. Even worse, the responsibility tends to rest on the team lead.

In the midst of the flurry of proposal writing, it may feel like a waste of time to bring in the development team to work on the estimates using a practice such as planning poker. Better use a shortcut and just call the most senior developer and have them give you the estimate.

In this entry, we will be looking at why this is a bad idea and why group estimates tend to fair better than individual estimates, no matter how senior the individual doing it.

The elephant in the room

An old Chinese parable explains this concept very well. Here is the story quoted verbatim:

    Once upon a time, there lived six blind men in a village. One day the villagers told them, "Hey, there is an elephant in the village today."
    They had no idea what an elephant is. They decided, "Even though we would not be able to see it, let us go and feel it anyway." All of them went where the elephant was. Everyone of them touched the elephant.
    "Oh, no! it is like a rope," said the second man who touched the tail.
    "Oh, no! it is like a thick branch of a tree," said the third man who touched the trunk of the elephant.
    "It is like a big hand fan" said the fourth man who touched the ear of the elephant.
    "It is like a huge wall," said the fifth man who touched the belly of the elephant.
    "It is like a solid pipe," Said the sixth man who touched the tusk of the elephant.
    They began to argue about the elephant and everyone of them insisted that he was right. It looked like they were getting agitated. A wise man was passing by and he saw this. He stopped and asked them, "What is the matter?" They said, "We cannot agree to what the elephant is like." Each one of them told what he thought the elephant was like. The wise man calmly explained to them, "All of you are right. The reason every one of you is telling it differently because each one of you touched the different part of the elephant. So, actually the elephant has all those features what you all said."

    Source: [jainworld](https://www.jainworld.com/literature/story25.htm)

The idea behind this story is that we all have different viewpoints. Until the software product is complete, it is mostly a jumbled mess. Everyone in the team sees only a small part of what the work would entail.

In short, you need the whole team to see the elephant.

Human folly

As a species, we named ourselves Homo Sapiens literally translates to wise man. We couldn’t have been any more wrong in this assessment.

Human reasoning is terribly flawed. The list of our biases is so long that not even a single volume would be able to contain it all. That is not to say they have not tried, see Predictably Irrational, Misbehaving and many other such titles.

Wikipedia has a list so long that it would fit a couple of articles and that is not considering their definitions.

In short, when an individual does the estimates. They will probably seek reasons why their estimate was right rather than getting to the right estimate.

Thankfully, we also evolved a way to combat our biases, arguments. Constructive arguments around the estimate will help everyone think more carefully about their estimate and thus raise the overall quality of the final estimate.

Deep understanding

In an article Minding matter, the astronomer Adam Frank says something very interesting

    When I was a young physics student I once asked a professor: ‘What’s an electron?’ His answer stunned me. ‘An electron,’ he said, ‘is that to which we attribute the properties of the electron’

He does go on to explain the statement. For the sake of this entry, it suffices to acknowledge that the reality of what the product will be is as much what the developers will make it, as it is what we think is an objective product out there.

If this is the case, then understanding the different viewpoints can help us get a far clearer picture of what the developers intend to build and thus a better estimate of the size and effort required.

The rule of five

I like the quote

    Always remember that you are absolutely unique. Just like everyone else.
    Margaret Mead

It reminds us that at the end of the day, our estimates will likely cluster. This is not folksy wisdom. It is a statistical fact. There is a 93.75% chance that the median of a population is between the smallest and largest values in any random sample of five from that population.

Take this rule in comfort, it means that while there is a great benefit to having a group do the estimates, the group needs not be bigger than just 5 individuals.

Do you do estimation in groups in your own organisation? Talk to me in the comment section below or on my twitter @jchex

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jchencha

API Engineer