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• ## Re: [XP] Units of time for estimates

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• ... Because velocity changes. Having velocity be a map from points to hours makes this easy to understand. Having velocity be a unitless number that maps
Jun 29, 2001 1 of 4
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--- Torben_W�lm <torben.wolm@...> wrote:
> I got a hard question from my manager the other day:
>
> "Why are 'points' a better measure than 'hours'?"

Because velocity changes. Having velocity be a map from points to hours
makes this easy to understand. Having velocity be a unitless number
that maps "estimated hours" to "actual hours" confuses people. You will
quote numbers in (estimated) hours and your manager will assume they
are actual hours.

Our Master Plan is in points. Every iteration, I update the forecast of
when I think we will finish by diving remaining points be velocity
(points per iteration) to get # of iterations to completion. I do much
less work updating the plan than I used to (pre-XP) when all of the
estimates were in hours. My updating is more accurate because I use my
current velocity to forecast everything, and don't try to live in the
fantasy world of many project plans that assume future estimates to be
accurate even though all completed tasks have taken longer than
estimated (or worse yet the ultra-fantasy world where future tasks are
completed faster than estimated to compensate for completed tasks
having taken longer than estimated).

Regards,

Rob

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• ... You guys are starting to convince me ... tell me more, points users! Ronald E Jeffries http://www.XProgramming.com http://www.objectmentor.com
Jun 29, 2001 1 of 4
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Responding to Robert Sartin (08:54 AM 6/29/2001 -0700):
>Because velocity changes. Having velocity be a map from points to hours
>makes this easy to understand. Having velocity be a unitless number
>that maps "estimated hours" to "actual hours" confuses people. You will
>quote numbers in (estimated) hours and your manager will assume they
>are actual hours.

You guys are starting to convince me ... tell me more, points users!

Ronald E Jeffries
http://www.XProgramming.com
http://www.objectmentor.com
• ... My team uses a wiki to display to the rest of our company the tasks we are doing this week. Any bug fixes that are demanded but were not originally
Jul 2, 2001 1 of 4
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> Maybe all our trouble started here. She wanted to know exactly why we were
> not faster. Part of it was significant changes in some of the stories
> (zeroing out some of the effort spent), but the real time consumers were non
> project related tasks. Old systems needed attention and servers were
> breaking down. And probably the hours spent on these tasks were not
> compatible with the point system. I don't know.

My team uses a wiki to display to the rest of our company the tasks we are
doing this week. Any bug fixes that are demanded but were not originally
scheduled would show up on the this-week's-tasks wiki page. Estimated time
(in days) and actual time (when a task is done) are listed with each task.

Since we have about six projects to be done by three people -- most of the
projects are inactive except for occasional bug fixes, which often have
'must be done immediately' priority -- it seems to be very important to let
all the people who demand our time be aware of the other demands on our
time.

Sometimes we get them into a meeting or virtual meeting to determine the
relative priorities of projects, so one or two project can be completely
ignored in favor or others for a few weeks at a time.

When you have multiple projects, perhaps estimating stories and tasks in
[fractions of] days is better than using points. It is also difficult to
have fixed-length iterations when you have multiple projects -- for some
purposes, we have one-week iterations, but inactive/bug-fix projects get
built and deployed whenever a bug is fixed.

It might even be worth putting meetings (and their actual times) into the
task list, when the whole team has to attend a meeting of one hour or more.

----

C. Keith Ray
<http://homepage.mac.com/keithray/resume.html>
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