reid@decwrl.UUCP (Brian Reid) (10/01/86)
USENET READERSHIP SUMMARY REPORT for Sep 86
This is a monthly posting from the USENET Measurement Project at the DEC
Western Research Laboratory in Palo Alto, California.
This survey is based on a sample of data taken from various USENET sites.
At the end of this message there is a short explanation of the measurement
techniques and the meaning of the various statistics.
The complete set of readership data (of which this is a summary) is posted
in mod.newslists
Brian Reid
OVERALL SUMMARY:
This Estimated
Sample for entire net
Sites: 395 4500
Fraction reporting: 8.78% 100%
Users with accounts: 55493 632000
Netreaders: 11721 133000
Average readers per site: 30
Percent of users who are netreaders: 21.12%
Average traffic per day (megabytes): 1.471
Average traffic per day (messages): 633
Traffic measurement interval: last 21 days
Readership measurement interval: last 75 days
TOP 40 NEWSGROUPS IN ORDER BY POPULARITY
+-- Estimated total number of people who read the group, worldwide.
| +-- Actual number of readers in sampled population
| | +-- Recent traffic, in messages per month.
| | | +-- Recent traffic, in kilobytes per month.
| | | | +-- Participation ratio: msgs/month/Krdrs
| | | | | +-- Cost ratio: $US/month/reader
| | | | | | +-- Rating: % of all users who
| | | | | | | read this group.
| | | | | | | +-- Share: % newsreaders
| | | | | | | | who read this group.
V V V V V V V V
1 28000 2751 42 76.0 1 0.01 5.0% 23.5% net.general
2 24000 2353 380 488.6 15 0.08 4.2% 20.1% net.jokes
3 24000 2338 102 1066.0 4 0.18 4.2% 19.9% net.sources
4 20000 1951 17 421.7 0 0.08 3.5% 16.6% mod.sources
5 19000 1850 82 194.1 4 0.04 3.3% 15.8% net.jobs
6 16000 1514 1 2.6 0 0.00 2.7% 12.9% mod.announce
7 15000 1509 249 394.5 16 0.10 2.7% 12.9% net.unix
8 15000 1417 435 825.1 29 0.22 2.6% 12.1% net.singles
9 14000 1394 254 408.8 18 0.12 2.5% 11.9% net.unix-wizards
10 14000 1383 100 107.0 7 0.03 2.5% 11.8% net.wanted
11 14000 1358 20 179.4 1 0.05 2.4% 11.6% net.sources.games
12 14000 1319 55 105.4 3 0.03 2.4% 11.3% net.ai
13 13000 1293 185 247.9 14 0.08 2.3% 11.0% net.micro
14 13000 1291 38 92.4 2 0.03 2.3% 11.0% net.sources.bugs
15 13000 1225 231 500.6 17 0.15 2.2% 10.5% net.arch
16 13000 1221 492 886.7 37 0.27 2.2% 10.4% net.micro.mac
17 12000 1218 388 1336.0 32 0.44 2.2% 10.4% net.micro.pc
18 12000 1214 227 347.4 18 0.11 2.2% 10.4% net.lang.c
19 12000 1195 74 122.2 6 0.04 2.2% 10.2% net.graphics
20 12000 1189 100 134.8 8 0.04 2.1% 10.1% net.movies
21 12000 1173 291 491.6 24 0.16 2.1% 10.0% net.audio
22 12000 1151 11 27.1 0 0.01 2.1% 9.8% net.announce.arpa-i
23 12000 1143 52 70.0 4 0.02 2.1% 9.8% net.sources.d
24 11000 1119 7 7.4 0 0.00 2.0% 9.5% net.rumor
25 11000 1100 138 212.4 12 0.08 2.0% 9.4% net.consumers
26 11000 1097 60 120.5 5 0.04 2.0% 9.4% net.news
27 11000 1083 5 12.7 0 0.00 2.0% 9.2% mod.newprod
28 11000 1041 105 97.1 9 0.03 1.9% 8.9% net.wanted.sources
29 10000 1003 104 252.4 10 0.10 1.8% 8.6% net.news.group
30 10000 995 150 253.4 15 0.10 1.8% 8.5% net.women
31 10000 984 110 180.8 11 0.07 1.8% 8.4% net.misc
32 10000 981 60 97.5 6 0.04 1.8% 8.4% net.books
33 10000 971 5 19.2 0 0.01 1.7% 8.3% mod.conferences
34 9600 937 128 156.1 13 0.06 1.7% 8.0% net.cooks
35 9600 932 120 170.9 12 0.07 1.7% 8.0% net.invest
36 9500 928 30 1401.6 3 0.58 1.7% 7.9% net.sources.mac
37 9500 925 58 142.7 6 0.06 1.7% 7.9% net.emacs
38 9300 907 432 769.6 46 0.33 1.6% 7.7% net.auto
39 9300 907 15 20.2 1 0.01 1.6% 7.7% net.lang
40 9100 891 30 49.5 3 0.02 1.6% 7.6% net.lan
TOP 40 NEWSGROUPS IN ORDER BY PER-READER COST
+-- Estimated total number of people who read the group, worldwide.
| +-- Actual number of readers in sampled population
| | +-- Recent traffic, in messages per month.
| | | +-- Recent traffic, in kilobytes per month.
| | | | +-- Participation ratio: msgs/month/Krdrs
| | | | | +-- Cost ratio: $US/month/reader
| | | | | | +-- Rating: % of all users who
| | | | | | | read this group.
| | | | | | | +-- Share: % newsreaders
| | | | | | | | who read this group.
V V V V V V V V
1 660 64 410 1359.1 621 8.10 0.1% 0.5% talk.politics.misc
2 680 66 314 833.2 462 4.80 0.1% 0.6% talk.religion.misc
3 790 77 107 301.1 135 1.50 0.1% 0.7% talk.origins
4 640 62 104 233.5 162 1.40 0.1% 0.5% talk.philosophy.mis
5 5000 487 591 1206.4 118 0.95 0.9% 4.2% net.comics
6 8700 844 755 1430.9 86 0.65 1.5% 7.2% net.sf-lovers
7 5600 549 482 865.2 86 0.61 1.0% 4.7% net.micro.atari16
8 9500 928 30 1401.6 3 0.58 1.7% 7.9% net.sources.mac
9 3200 316 20 426.0 6 0.53 0.6% 2.7% mod.politics.arms-d
10 800 78 45 105.2 57 0.52 0.1% 0.7% talk.abortion
11 6000 589 21 773.8 3 0.51 1.1% 5.0% mod.mac.binaries
12 3400 335 140 426.3 41 0.50 0.6% 2.9% net.religion.christ
13 2200 211 152 272.3 69 0.49 0.4% 1.8% mod.music.gaffa
14 2600 250 215 305.6 82 0.46 0.5% 2.1% talk.bizarre
15 12000 1218 388 1336.0 32 0.44 2.2% 10.4% net.micro.pc
16 8600 839 411 917.0 47 0.42 1.5% 7.2% net.micro.amiga
17 3800 370 212 385.2 56 0.40 0.7% 3.2% net.sport.baseball
18 2700 263 82 251.1 30 0.37 0.5% 2.2% net.micro.atari8
19 3800 373 185 347.0 48 0.36 0.7% 3.2% net.sport.football
20 5900 580 190 529.4 32 0.35 1.0% 4.9% net.politics
21 9300 907 432 769.6 46 0.33 1.6% 7.7% net.auto
22 8200 797 324 572.8 39 0.28 1.4% 6.8% net.space
23 7500 727 272 537.9 36 0.28 1.3% 6.2% net.med
24 13000 1221 492 886.7 37 0.27 2.2% 10.4% net.micro.mac
25 5600 542 27 387.8 4 0.27 1.0% 4.6% mod.risks
26 6200 609 221 375.7 35 0.24 1.1% 5.2% net.startrek
27 3700 361 72 226.4 19 0.24 0.7% 3.1% net.religion.jewish
28 6700 653 20 389.7 2 0.23 1.2% 5.6% mod.mac
29 15000 1417 435 825.1 29 0.22 2.6% 12.1% net.singles
30 5700 552 78 311.0 13 0.22 1.0% 4.7% net.motss
31 4900 481 98 271.9 20 0.22 0.9% 4.1% mod.politics
32 4700 456 132 262.4 28 0.22 0.8% 3.9% net.ham-radio
33 4800 468 4 249.0 0 0.20 0.8% 4.0% mod.amiga.sources
34 2900 284 82 145.9 28 0.20 0.5% 2.4% net.music.makers
35 5800 567 170 280.0 29 0.19 1.0% 4.8% net.aviation
36 24000 2338 102 1066.0 4 0.18 4.2% 19.9% net.sources
37 3900 379 67 176.7 17 0.18 0.7% 3.2% net.religion
38 2400 238 22 104.8 9 0.17 0.4% 2.0% net.rec.bridge
39 12000 1173 291 491.6 24 0.16 2.1% 10.0% net.audio
40 8300 805 247 328.1 29 0.16 1.5% 6.9% mod.computers.vax
TOP 40 NEWSGROUPS IN ORDER BY MESSAGES PER READER
+-- Estimated total number of people who read the group, worldwide.
| +-- Actual number of readers in sampled population
| | +-- Recent traffic, in messages per month.
| | | +-- Recent traffic, in kilobytes per month.
| | | | +-- Participation ratio: msgs/month/Krdrs
| | | | | +-- Cost ratio: $US/month/reader
| | | | | | +-- Rating: % of all users who
| | | | | | | read this group.
| | | | | | | +-- Share: % newsreaders
| | | | | | | | who read this group.
V V V V V V V V
1 660 64 410 1359.1 621 8.10 0.1% 0.5% talk.politics.misc
2 680 66 314 833.2 462 4.80 0.1% 0.6% talk.religion.misc
3 640 62 104 233.5 162 1.40 0.1% 0.5% talk.philosophy.mis
4 790 77 107 301.1 135 1.50 0.1% 0.7% talk.origins
5 5000 487 591 1206.4 118 0.95 0.9% 4.2% net.comics
6 8700 844 755 1430.9 86 0.65 1.5% 7.2% net.sf-lovers
7 5600 549 482 865.2 86 0.61 1.0% 4.7% net.micro.atari16
8 2600 250 215 305.6 82 0.46 0.5% 2.1% talk.bizarre
9 2200 211 152 272.3 69 0.49 0.4% 1.8% mod.music.gaffa
10 800 78 45 105.2 57 0.52 0.1% 0.7% talk.abortion
11 3800 370 212 385.2 56 0.40 0.7% 3.2% net.sport.baseball
12 3800 373 185 347.0 48 0.36 0.7% 3.2% net.sport.football
13 8600 839 411 917.0 47 0.42 1.5% 7.2% net.micro.amiga
14 9300 907 432 769.6 46 0.33 1.6% 7.7% net.auto
15 3400 335 140 426.3 41 0.50 0.6% 2.9% net.religion.christ
16 8200 797 324 572.8 39 0.28 1.4% 6.8% net.space
17 13000 1221 492 886.7 37 0.27 2.2% 10.4% net.micro.mac
18 7500 727 272 537.9 36 0.28 1.3% 6.2% net.med
19 6200 609 221 375.7 35 0.24 1.1% 5.2% net.startrek
20 12000 1218 388 1336.0 32 0.44 2.2% 10.4% net.micro.pc
21 5900 580 190 529.4 32 0.35 1.0% 4.9% net.politics
22 6800 667 205 257.6 30 0.15 1.2% 5.7% net.video
23 2700 263 82 251.1 30 0.37 0.5% 2.2% net.micro.atari8
24 15000 1417 435 825.1 29 0.22 2.6% 12.1% net.singles
25 8300 805 247 328.1 29 0.16 1.5% 6.9% mod.computers.vax
26 5800 567 170 280.0 29 0.19 1.0% 4.8% net.aviation
27 4700 456 132 262.4 28 0.22 0.8% 3.9% net.ham-radio
28 2900 284 82 145.9 28 0.20 0.5% 2.4% net.music.makers
29 8800 861 240 323.8 27 0.15 1.6% 7.3% net.music
30 12000 1173 291 491.6 24 0.16 2.1% 10.0% net.audio
31 6600 648 158 203.9 24 0.12 1.2% 5.5% net.consumers.house
32 3400 335 78 34.8 23 0.04 0.6% 2.9% net.test
33 4600 447 97 137.4 21 0.12 0.8% 3.8% net.micro.cpm
34 3800 374 80 113.8 21 0.12 0.7% 3.2% net.tv.drwho
35 4900 481 98 271.9 20 0.22 0.9% 4.1% mod.politics
36 6800 662 132 168.3 19 0.10 1.2% 5.6% net.tv
37 6000 586 115 181.6 19 0.12 1.1% 5.0% mod.protocols.tcp-i
38 4700 460 90 134.0 19 0.11 0.8% 3.9% net.music.synth
39 3700 361 72 226.4 19 0.24 0.7% 3.1% net.religion.jewish
40 14000 1394 254 408.8 18 0.12 2.5% 11.9% net.unix-wizards
BOTTOM 10 NEWSGROUPS IN ORDER BY POPULARITY
+-- Estimated total number of people who read the group, worldwide.
| +-- Actual number of readers in sampled population
| | +-- Recent traffic, in messages per month.
| | | +-- Recent traffic, in kilobytes per month.
| | | | +-- Participation ratio: msgs/month/Krdrs
| | | | | +-- Cost ratio: $US/month/reader
| | | | | | +-- Rating: % of all users who
| | | | | | | read this group.
| | | | | | | +-- Share: % newsreaders
| | | | | | | | who read this group.
V V V V V V V V
214 2200 211 152 272.3 69 0.49 0.4% 1.8% mod.music.gaffa
215 2100 204 10 11.3 4 0.02 0.4% 1.7% net.rec.drugs
216 2100 201 17 37.2 8 0.07 0.4% 1.7% talk.religion
217 800 78 45 105.2 57 0.52 0.1% 0.7% talk.abortion
218 790 77 107 301.1 135 1.50 0.1% 0.7% talk.origins
219 680 66 314 833.2 462 4.80 0.1% 0.6% talk.religion.misc
220 660 64 410 1359.1 621 8.10 0.1% 0.5% talk.politics.misc
221 640 62 104 233.5 162 1.40 0.1% 0.5% talk.philosophy.mis
222 440 43 5 10.8 12 0.10 0.1% 0.4% talk.politics.theor
223 320 31 4 8.9 13 0.11 0.1% 0.3% mod.religion.christ
Valid data received from these sites:
3d.dec.com a60 aaec acetes adelie aero aero2 akgua akgub akguc akgud
akov68.dec.com alberta alliant altos.dec.com alv amdahl amdcad ames
angora.dec.com argus arthur arthur.cs.purdue.edu asd.dec.com
ashby.dec.com astrovax atari athena aurora author.dec.com axis basser
baxta.dec.com bcm5000 bcse.dec.com bemis.dec.com bene beno beno.css.gov
bigbang bizet.dec.com bms-at bnl brand brspyr1 btnix bu-cs bubba
bucsb.bu.edu bucsd cadomin cae780 caip.rutgers.edu calay calgary carmel
cascade castor.dec.com cavell cbosgd ccvaxa cesare.dec.com
cgfsv1.dec.com cgl.ucsf.edu chalmers charon.dec.com cheviot chinet
chronon ci-dandelion circe cisunx cit-vax clio clt.dec.com cognos
concurrent.co.uk cookie.dec.com cooper cortex cory.berkeley.edu
covert.dec.com cp1 cpsc53 cpw.columbia.edu crcge1 crvax1.dec.com
cs.nott.ac.uk csadfa csustan cuae2 curium.dec.com cuuxb cvl cwruecmp
cxsea dalcs darth dayton dciem dcl-csvax deceat.dec.com decuac decwrl
desint diablo diamond.bbn.com dione dmcnh down dregs.dec.com drillsys
dssdev.dec.com dukempd dycom ector.cs.purdue.edu edison
elbereth.rutgers.edu elsie elwood.dec.com ems endor entropy eros ethos
euclid.dec.com exodus.dec.com fai felix foxvax5 fritz ganash gatech
gitpyr glacier godot gollum.dec.com gouldsd grc97 grebyn gt-stratus
gvaic2.dec.com h-sc4 h.cc.purdue.edu hao hc.dspo.gov hdsvx1 hercules
hjuxa hpldora hscfvax hutch i.cc.purdue.edu iapetus ic ichaya ihu1n
im4u ima imagen imt3b2 indian.dec.com infinet infopro iscuva ishtar
isis istg.dec.com ittvax j.cc.purdue.edu jasper jimi jon.dec.com
jplgodo k.cc.purdue.edu kaoa01.dec.com killer kirk.dec.com kodak
koning.dec.com kosman kpe l.cc.purdue.edu labrea lando.dec.com
lerouf.dec.com lll-crg lll-lcc luke lymph.dec.com macbeth maccunix
majestix masscomp maynard mcc-pp mcgill- mcgill-vision mck-csc me-ncr
meccts midacs mips mirror mit-trillian mnetor mntgfx mojave.dec.com
moncol mordred mordred.cs.purdue.edu mormps.dec.com mss msudoc mtgzy
mtgzz munsell myrias naakka nac.dec.com nacho.dec.com navajo nbires
ncoast ncr-sd ncrcae ncsuvx nesterc nike njitcccc noao nonode.dec.com
novavax nsc nssg.dec.com nttlab nutmeg.dec.com nymgr.dec.com oblio
oblio.dec.com ocean oddjob ohgua ohgub ohguc onecom opus opus.dec.com
orion osiris parity.dec.com pbhya pegasus philabs phoenix phri phuxa
phuxc pipa.dec.com pitt pixar pldvax.dec.com plus5 pogo popeye poseidon
potomac princeton ptsfa ptsfb ptsfc ptsfd pulman.dec.com qantel qnda01
quad1 ra rainbo.dec.com raster rayssd rdlvax regent.dec.com
rhea.dec.com rlvd rochester rocky rosevax royce.dec.com rtech rti-sel
saber samira sandia sandoz saturn sauron scicom scribe.dec.com sdcc12
sdcc13 sdcc3 sdcc6 sdcc7 sdcsvax se-sd seismo shasta sicsten sigma soma
spar sphinx sri-spam ssc-vax star.dec.com stride styx su-isl suadb
sunybcs tallis.dec.com teklds telesoft tflop tilt tipple.dec.com titan
tonto.dec.com topaz.rutgers.edu truman.dec.com tuck tucos turtlevax tut
tutctl tymix ucla-cs uiucuxa uiucuxc uiucuxe uiucuxf ujocs ukma ulowell
ultra.dec.com umd-cs umd-ua umd5.umd.edu umn-cs unirot uqcspe.oz
usc-oberon usrcv1.dec.com ut-sally utah-cs utah-gr utcs uwmacc
vaxuum.dec.com vianet video.dec.com vino.dec.com voder vu-vlsi vulcan
walldata wang7 wanginst watale watarts watcal watcgl watdaisy watdcsu
watdragon wateng water watlion watmath watmum watnot watopt watpix
watrose watvlsi well wjh12 wolf wuphys yale yarra yoda.dec.com
yogi.dec.com zeus zhora.dec.com
------------------------------------------------------------------------------
EXPLANATION OF THE MEASUREMENTS AND STATISTICS
Survey data is taken by having one person at each site run a program called
"arbitron", which looks at the news or notes files and determines the
newsgroups that the user has read within a recent interval. To "read" a
newsgroup means to have been presented with the opportunity to look at at
least one message in it. Going through a newsgroup with the "n" key counts
as reading it. For a news site, "user X reads group Y" means that user X's
.newsrc file has marked at least one unexpired message in Y. If there is no
traffic in a newsgroup for the measurement period, then the survey will show
that nobody reads the group. For a notes site, "user X reads group Y" means
that user X has been in the notesfile with the sequencer in the last 14 days.
The "14 days" interval for notesfiles corresponds to "unexpired" for news.
The "arbitron" program is periodically posted to net.sources, or is available
from me (decwrl!reid). The notesfiles version of the program should be
available through standard notesfiles software distribution channels as well.
SITES SURVEYED IN THIS SAMPLE
"This Sample" means the set of sites that have sent in an arbitron report
within the past "Readership measurement interval" days. In every case the
most recent report from each site is used. At the moment, some of the
readership reports are several months old. In future postings those reports
will have expired and will not be included.
One might argue that the sample is self-selected, like the famous Literary
Digest Dewey-Truman election poll sample. It does in fact have a certain
self-selection factor in it, because we only get data from sites at which
someone participates in the survey. However, we do not require the
participation of every user at a site, only one user. The survey program
returns data for every user on the system on which it was run. Since there
are an average of 30 people per site reading news, there is a certain amount
of randomness introduced that way. Of course, the sample is biased in favor
of large sites (they are more likely to have a user willing to run the survey
program) and software-development-oriented sites (more likely to have a user
*able* to run the survey program). I intend to post, reasonably soon, some
breakdowns of statistics about the sites that have responded.
NETWORK SIZE
I determine the network size by looking at the set of sites that are
mentioned in the Path lines of news articles arriving at decwrl. This number
is consistently higher than the number of sites that posted a message (as
measured and posted from Seismo) because it includes passive sites that are
on the paths between posting sites and decwrl. Each month I store the names
of the hosts that are named that month, and for this report I used the past
6 months worth of data.
There are 4422 different sites in the Path lines of articles that
arrived at decwrl in the last 6 months. There are 5559 different sites in
the mod.map data, but mod.map includes every site that participates in uucp;
there is a considerable number of machines that exchange uucp mail but do not
get USENET. Of those 4422 sites, 69 (1%) are DEC E-net hosts not part of
uucp, and which therefore are not included in the 5559 figure.
Despite these various difficulties, I believe that 4500 is the best
estimate for the size of USENET. Because it is actually a measurement of the
number of sites that have posted a message or that are on the path to a site
that has posted a message, it will be slightly smaller than the number of
sites that actually read netnews. Any site that believes it is not being
counted can just ensure that it posts at least one message a year, so that
it will be counted.
NUMBER OF USERS
The number of users at each site is determined in a site-specific fashion.
Sometimes it is done by counting the number of user accounts that have
shells and login directories. Sometimes it is done by counting the number of
people who have logged in to the machine in some interval. Sometimes other
techniques are used. This number is probably not very accurate--certainly
not more accurate than to within a factor of two.
ESTIMATED TOTAL NUMBER OF PEOPLE WHO READ THIS GROUP, WORLDWIDE
There are two sources of error in this number. The number is computed by
multiplying the number of people in the sample who actually read the group by
the ratio of estimated network size to sample size. The estimated total can
therefore be biased by errors in the network size estimate (see above) and
also by errors in the determination of whether or not someone reads a group.
Assuming that "reading a group" is roughly the same as "thumbing through a
magazine", in that you don't necessarily have to read anything, but you have
to browse through it and see what is there, then the measurement error will
come primarily from inability to locate .newsrc files, which can either be
protected or moved out of root directories. There is no way of measuring the
effect on the measurements from unlocated .newsrc files, but it is not likely
to be more than a few percent of the total news readers.
MESSAGES PER MONTH AND KILOBYTES PER MONTH
Traffic is measured at decwrl, in Palo Alto, California. Any message that has
arrived at decwrl within the last "Traffic measurement interval" days is
counted, regardless of when it was posted. Monthly rates are computed by
taking the total traffic, dividing by the number of days in the traffic
measurement interval, and multiplying by 30. Decwrl runs 2.10.3 news, which
does not store the "Date-Received", "Relay-version" or "Posting-version"
header lines; the amount of space occupied at your site might be higher, and
the number of bytes transmitted between machines is probably higher. By
definition this number is correct, because it is an exact measurement, but it
may differ from the traffic at your site by as much as 15% due to timing
differences and news version differences. Timing differences will be random,
but will average out in the long run. News version differences will cause a
systematic error that is additively uniform across all newsgroups, and which
therefore does not significantly affect ratios.
If a message is crossposted to several groups simultaneously, it is charged
only to the first-named group in the list.
PARTICIPATION RATIO: MESSAGES per MONTH per 1000 READERS
This number is exactly what it says: the number of messages per month in
that newsgroup, divided by the number of 1000 readers. It is an indication
of how involved the readers of the group are in the traffic, of whether they
are mostly listeners or mostly talkers. Its accuracy is limited by the
accuracy of its two components. The messages per month figure is exact; the
reader count is only as accurate as the network size estimate, which is in
worst case accurate to 40%. Therefore you should treat this number as having
an error margin of plus or minus 40%. However, ratios between participation
ratios for different newsgroups are quite accurate, since the network-size
component divides out.
COST RATIO: DOLLARS PER MONTH PER READER
The most controversial field in the survey report is the "$US per month per
reader". It is the estimated number of dollars that are being spent on
behalf of each reader, worldwide, on telephone costs to transmit this
newsgroup. The cost ratio does not include the cost of disk storage to store
the news or of computer time to process it; both of those are assumed to be
free.
The cost ratio is computed as follows:
$US/month/reader = ($USPerMonthPerSite * numberOfSites) / numberOfReaders
$USPerMonthPersite = KBytesTrafficPerMonth * $USPerKByte
$USPerKByte = ($USperMinute / KBytesPerMinute) * (1 - CompressionFactor)
$USperMinute = 0.10 [ten cents per minute avg phone cost]
KBytesPerMinute = 60 * BytesPerSecond / 1000
BytesPerSecond = 100 [average transfer rate over 1200-baud line]
CompressionFactor = 0.4 [40% compression is typical for netnews]
Combining all these gives
$USPerMonthPersite =
KBytesTrafficPerMonth * (0.10 / 6) * (1 - 0.4)
= KBytesTrafficPerMonth / 100
Therefore:
$US/month/reader =
(KBytesTrafficPerMonth * numberOfSites) / (100 * numberOfReaders)
The accuracy of this number is in fact better than the accuracy of the
participation ratio, because the source of error--the network size
estimate--is present both in the numerator and the denominator, and therefore
cancels out. The primary source of bias in this number comes from the bias in
the "estimated number of readers, worldwide", which is described above. Treat
this value as being accurate to within about 25%.
SITE PARTICIPATION
I would like to receive data from every site on USENET. The arbitron programs
(posted to net.sources along with this report) work on news 2.9 and 2.10.[1-3]
and on many versions of notesfiles.
Brian Reid
DEC Western Research Laboratory, Palo Alto CA
reid@decwrl.DEC.COM
{ihnp4,allegra,decvax,ucbvax,sun,glacier}!decwrl!reid