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Some Implications of Bazaar Size

Third Draft. Aug 11, 1998
Copyright 1997-1998, Forrest J. Cavalier, III Mib Software
All rights reserved. Comments welcome!

1. The Importance of Bazaar "Effective Size"

Implicit in some of Eric Raymond's description of a successful Bazaar development method, is the notion of the bazaar being "large-enough" to find bugs quickly, or "self-sustaining." While his writing seems to imply that size does affect success, this is not stated or discussed directly.

I hold that size is very important, and discuss reasons for this view.

Comments on bazaar size as a precondition
Raymond speaks of preconditions for a successful bazaar. I asked about the size of the developer pool (who will start the bazaar) as a precondition, since this was not mentioned.
His "off the top of his head" comment was:
"....thinking in terms of a hard minimum number of participants is misleading. Fetchmail and Linux have huge numbers of beta testers *now*, but they obviously both had very few at the beginning.

What both projects did have was a handful of enthusiasts and a plausible promise. The promise was partly technical (this code will be wonderful with a little effort) and sociological (if you join our gang, you'll have as much fun as we're having). So what's necessary for a bazaar to develop is that it be credible that the full-blown bazaar will exist!"

Implicit in these and other comments is that there is some minimum number of participants in order to have a successful bazaar. How many is "too small" to successfully apply bazaar development concepts?

Raymond does not define "bazaar" in a concrete way which would allow defining a "size measurement." I define three size measurements for bazaars: "total size" and "effective size", and "effective power."

"Specific activity" is very important to effective size. Bazaars may have very large effective sizes for some activities and not others. For example, a bazaar with a size of 5000 may only have an effective size of 5 (or even less than 1) for an unpopular activity such as documentation or regression testing. This may be due to lack of motivation or inability to contribute. (Many bazaar efforts are volunteer efforts.)

Effective power is a function of effective size AND the activity level of the participants. It is possible to have one participant contribute more or less than another. One highly active participant may contribute as much work per week as 5 or 10 less active ones combined. Bazaars with more highly motivated and active individuals have larger effective powers.

Types of bazaar participants
In order to try to count the participants for discussing the size of a bazaar, I break the participants into three main types/profiles based on their reason for participating and level of involvement. An individual person may move between different profiles over time, or even play roles in multiple profiles simultaneously.

Observations on effective size and power

[1] (April 2001). David Isecke pointed out that this statement can be confusing, because "effective size" is defined to measure the bazaar, not the requirements of each step. The next bulleted item states it more clearly.

Next 2. Debugging by testing dramatically lowers effective size
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