RE: SIP is not Takt Time

Steve,

I didn't state it in my initial post on this thread
but I very much believe that inventory (and I would
like SIP to be a measure of inventory) should be
stated as "Story points in progress". Stories are to
my mind the unit of production in XP. They represent
the ideas going into the software development system
and the value coming out of it as working code.

Your "weeks per story point" measure is comparable to
the measure used in Lean Production e.g. hours per
vehicle.

This metric measures the efficiency of the flow of the
inventory (or the capital deployed in the inventory)
rather than the efficiency of the man or machine which
is the approach taken in mass production - based on
Taylor's scientific management - and unltimately
traced back to Adam Smith's "division of labour".

Hence, I agree with you entirely. Inventory in XP
should be "Story Points In Progress" and this to my
mind should be the SIP measure.

It would be possible to simply use "Stores in
progress" and accept that there was a greater
uncertainty attached to the measurement.

In FDD I already use "Features in progress" as the
inventory measure, and I have classified a 5 point
scale for "complexity" of Features - these are similar
to Story Points.

Hence, an FDD equivalent to Story Points in Progress
would be FDD Feature Compexity In Progress.

I'm am completing a book "Agile Management" which
touches on this topic. I'm posting the 2nd draft
chapter-by-chapter for a limited time period at
http://www.uidesign.net/. The book is due to be
published by Prentice Hall in June.

Regards,

David

--- Steve Hayes <[email protected]> wrote:

>> not Takt time (takt in XP is always one week, we
>> just vary the size of the unit of production.)
>>

>I don't think it's true that in XP takt is one week.
>That's just the time 
>frame we use for velocity measurements. Takt is an
>inverse measurement of 
>velocity (instead of widgets per unit time, it
>states time per widget). XP 
>has a concept of velocity, measure in story points
>per week (iteration). 
>The inverse of this is weeks per story point, which
>isn't very satisfying, 
>but isn't one either.

>So for a given XP project, I could calculate takt
>time of, say, one day per 
>story point, and see if I was meeting this target or
>not. If we could 
>measure the velocity of story points at different
>parts of the value chain, 
>we could find bottlenecks or wastage, as in the
>example on the web page. 
>It's not clear to me how to do this, or if it's even
>worth trying.

>Steve


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