RE: Re: SIP is "just another Six Sigma measure"?

SIP is a bit confused WRT to the standard manufacturing terminology. If
you wanted a precise analog, it would be something like manufacturing
(or production) lead time. I want to get some more experience before I
change it, though, since the analogy is not precise in any case (as Mary
points out, we do a lot of simultaneous product development in the
software world that isn't part of manufacturing.)

For your example, I would calculate SIP of 140 if you didn't put any of
the features in production until they were all finished. The simplest
SIP reduction strategy is to find a way to ship half the features in
half the time. This only goes so far, though it is a good place to
start.

Does that answer your question?

Kent


-----Original Message-----
From:
sentto-8007113-377-1043230463-kent=threeriversinstitute.org@returns.grou
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[mailto:sentto-8007113-377-1043230463-kent=threeriversinstitute.org@retu
rns.groups.yahoo.com] On Behalf Of Dossy
Sent: Wednesday, January 22, 2003 2:14 AM
To: [email protected]
Subject: Re: [SIP] Re: SIP is "just another Six Sigma measure"?


On 2003.01.21, Tom Poppendieck <[email protected]> wrote:
> There is a very short tutorial on these manufacturing
> operations terms at
> http://hbswk.hbs.edu/pubcontent/toolkit/operations/index.html
> If you know how to do laundry, this introduction will be
> useful.

Thanks, Tom!  This is excellent.

On 2003.01.21, Kent Beck <[email protected]> wrote:
> 
> Suzuki "The New Manufacturing Challenge", p 131.
>   * Cycle time: Time between the completion of the last
> product and the completion of the next product
>   * Production lead time: Time between beginning of
> production and completion of production for a single product

Looking at the definitions presented by the Operations Basics Workbook
that Tom pointed us to, it seems that:

Cycle time: "Cycle Time is the length of time, on average, that it takes
to complete a step or set of steps within an operation."

Manufacturing Lead Time (MLT): "Manufacturing lead-time, or MLT, is the
average length of time it will take a new set of inputs to move all the
way through the operation, assuming no unusual measures are taken.
[...] Little's Law states that:
    Manufacturing Lead Time = Cycle Time * Work-in-Process"

Given this, Software-In-Process is the sum of Cycle Time of all the
steps required, since MLT accounts for Work-in-Process.
Software-Lead-Time (the analogue to MLT) would be "SIP * Number of
Features" ... right?

Or, are you really looking to make SIP identical to MLT?  In other
words, if we have 10 features to implement, and on average our
Conception phase takes 3 days (conception cycle time = 3 days), our
design/test/code phase takes 2 weeks (coding cycle time = 10 days) and
our customer review phase takes 1 day (review cycle time = 1 day),
therefore our whole process cycle time is 14 days ... times 10 features
yields a MLT of 140 days -- we'd have a SIP of 140 days?

-- Dossy

-- 
Dossy Shiobara                       mail: [email protected] 
Panoptic Computer Network             web: http://www.panoptic.com/ 
  "He realized the fastest way to change is to laugh at your own
    folly -- then you can let go and quickly move on." (p. 70)

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