Thursday, September 07, 2006

Nate Estimation

Well if innate estimation is what you do subconsciously, what do you do to estimate consciously? Hmm, well, let’s think. To estimate a task well is to consider how long it would take to complete satisfactorily: Mom said I can’t come out and play until my room is cleaned up. Well, how long will that take? Um, 5 minutes I guess.

Yeah, to who’s standard? Mom probably didn’t ask you to clean up your room cause it needs a mere surface cleaning and I assume you are not going to use heavy equipment, so your estimate probably does not take into account your customer’s standard of cleanliness.
So how long will it really take? There are two ways to define the effort for this task – first, set a timebox and clean as much as you can across that timebox. Your customer will probably accept this if a) the timebox is large enough to allow sufficient action and b) you work diligently across the entire timebox. The second way would be to sit down and understand what your customer’s expectations are and then examine the work from a task basis: 8 minutes to pick up dirty clothes, 12 to put the toys away and shelve the books, 10 to straighten and dust the furniture. There are no real uneventualities that may crop up to cause the estimates to be invalid; except perhaps if the monsters under the bed come out and start gnawing at your ankles while you work.

In most knowledge work, there are more unknowns that may complicate the task. But mostly, you are looking for tasks that may have some statistical variation to their completion. This is where the true joy of estimation really comes to fruition - another thing I learned building the house (truthfully, this I knew from 15 years ago during the early days of the CMM. Back then, we looked at other engineering disciplines like civil engineering to begin understanding why our software development processes were unable to establish some rigor about our work. My builder has been building for 20 years). As a funny aside, he is a good acquaintance of ours – he and my wife are both quite active in Rotary and the Boys and Girls Club in our area. He finds the frequency that I change employers some what interesting, since he has been self employed his entire life. So, as we were working on the house, he wanted to know about my current employer (Borland). Initially, the name meant nothing to him, as I expected, but then a spark lit up and he said “Visicalc! – that was my first spreadsheet!”


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