The experiment and the poll comes first as I don't want to infect you with my idea before you answer the questions. If you are in the mood of reading a short story and answering a couple of questions, keep reading. In case you are only concerned with my ideas, you may skip the first part.
I won't give any discussion about the subject. I'm just throwing my ideas to the internet, be warned.
Part 1. The experiment
You have to estimate the effort needed to complete a particular task of software development. You may use any tool you'd like to do it, but you will only get as much information as I will tell you now. You will use all the technologies that you already know, so you won't have any learning curve overhead and you will not encounter any technical difficulty when doing the task.
Our customer is bothered by missing other co-workers birthdates. He wants to know all co-workers that are cellebrating birthday or just cellebrated, so he can send a "happy birthday" message at the very morning, when he just turned on his computer. To avoid sending duplicated messages, he doesn't want to see the same person on multiple days at the list.
Your current sofware system already have all workers of the company with birthdates and their relationship, so you can figure out pretty easily who are the co-workers of the user and when is the birthdate of everyone.
Now, stop reading further, take your time and estimate the effort of this task by answering the following poll.
Okay, now I'll give you more information about it and ask for your estimate again.
Some religions do not celebrate birthdates and some people get really mad when receiving a message of "happy birthday". To avoid this, you also need to check if the user wants to make its birthdate public.
By the way, the customer's company closes at the weekend, so you need to take into account that at monday you will need to show birthdates that happened at the weekend and not only of the current day.
This also applies to holidays. The holidays are a bit harder as it depends on the city of the employee, as they may have different holidays.
Oh, and don't forget to take into account that the user may have missed a day, so it needs to see everyone that he would on the day that he missed the job.
Now, take your time and estimate again.
Part 2. The Dunning-Kruger effect on estimates
I don't know if the little story above tricked you or not, but that same story tricked me in real-life. :)
The Dunning-Kruger effect is stated at Wikipedia as:
"[...] a cognitive bias wherein relatively unskilled individuals suffer from illusory superiority, mistakenly assessing their ability to be much higher than is accurate. This bias is attributed to a metacognitive inability of the unskilled to accurately evaluate their own ability level. Conversely, highly skilled individuals may underestimate their relative competence, erroneously assuming that tasks that are easy for them are also easy for others."
I'm seeing that this effect contributes to make the task of estimating effort to be completely innacurate by nature, as it always pulls to a bad outcome. If you know little about it, you will overestimate your knowledge and consequently underestimate the effort to accomplish it. If you know much, you will underestimate your knowledge and consequently overestimate the effort.
I guess one way to minimize this problem is to remove knowledge up to the point that you only have left the essential needed to complete the task. Sort of what Taleb calls "via negativa" in his Antifragile book.
What do you think? Does this makes any sense to you?