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From: reid@glacier.ARPA (Brian Reid)
Newsgroups: net.news,net.news.group
Subject: Re: more interim results from worldwide net readership poll
Message-ID: <5641@glacier.ARPA>
Date: Mon, 24-Mar-86 20:00:25 EST
Article-I.D.: glacier.5641
Posted: Mon Mar 24 20:00:25 1986
Date-Received: Wed, 26-Mar-86 03:02:36 EST
References: <5192@glacier.ARPA> <1994@hao.UUCP> <5249@glacier.ARPA> <1998@hao.UUCP> <1165@utcs.uucp>
Reply-To: reid@glacier.UUCP (Brian Reid)
Organization: Stanford University, Computer Systems Lab
Lines: 33
Xref: watmath net.news:4692 net.news.group:5288

In article <1165@utcs.uucp> flaps@utcs.UUCP (Alan J Rosenthal) writes:

>Umm.. maybe I'm missing something obvious here but it seems to me that there
>is a big problem with these statistics.. I don't read nearly all of the
>groups in my .newsrc. My .newsrc contains the most number of groups I've
>EVER managed to catch up in. But they are in a careful order, and I rarely
>get to the end while reading. So, for example, I rarely read
>net.unix-wizards but am always subscribed to it. So wouldn't I be counted
>for that too?

No. The definition of "Person X reads group Y" is that person X's .newsrc
file shows that he has read (or marked as read) at least one message in
group Y that has not yet been expired. If "expire" is run with standard
options, this means that person X has read at least one message in that
newsgroup in the last two weeks. If your site expires more rapidly than two
weeks, then a more stringent test will be applied. 

This works by looking in the (2.10.2 and newer) active file to find the
"oldest unexpired message" and the "most recent message" numbers. Let N be
the number of the highest-numbered message in the .newsrc file that is shown
as having been read; you will be counted as reading the group if N is
greater than or equal to the oldest unexpired message number, less than or
equal to the most recent message number, and if the most recent message
number is greater than the oldest unexpired message number.

This algorithm could, of course, yield an erroneously large number of
subscribers for a group because of the "catch up" commands. However, what
the surveys show is that far LESS people read the newsgroups than anybody
had previously thought. For example, only about 3% of the sampled population
even bothers to list net.unix-wizards in their .newsrc at all.
-- 
	Brian Reid	decwrl!glacier!reid
	Stanford	reid@SU-Glacier.ARPA