reid@decwrl.UUCP (07/01/86)
USENET READERSHIP SUMMARY REPORT for Jun 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
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Recent change: crossposted messages are now counted only in the first
newsgroup in the list. For example, a message posted like this:
Newsgroups: net.politics,net.religion.jewish
will be counted in net.politics only.
----------------------------------------------------------------------------
OVERALL SUMMARY:
This Estimated
Sample for entire net
Sites: 376 1724
Fraction reporting: 21.81% 100.00%
Users with accounts: 49170 225000
Netreaders: 10935 50000
Average readers per site: 29
Percent of users who are netreaders: 22.24%
Average traffic per day (megabytes): 1.580
Average traffic per day (messages): 675
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 11000 2607 24 35.7 2 0.01 5.3% 23.8% net.general
2 11000 2600 4 11.6 0 0.00 5.3% 23.8% net.announce
3 10000 2432 582 655.1 58 0.25 4.9% 22.2% net.jokes
4 8100 1967 182 1524.7 22 0.71 4.0% 18.0% net.sources
5 6700 1632 110 276.1 16 0.15 3.3% 14.9% net.jobs
6 6600 1604 47 1481.3 7 0.84 3.3% 14.7% mod.sources
7 5300 1293 985 1665.1 185 1.20 2.6% 11.8% net.singles
8 5300 1288 358 603.4 67 0.43 2.6% 11.8% net.unix
9 5100 1242 290 541.0 56 0.40 2.5% 11.4% net.unix-wizards
10 5100 1241 190 295.5 37 0.22 2.5% 11.3% net.micro
11 5100 1235 108 111.4 21 0.08 2.5% 11.3% net.wanted
12 4800 1162 167 201.9 34 0.16 2.4% 10.6% net.rumor
13 4800 1161 212 303.1 44 0.24 2.4% 10.6% net.audio
14 4800 1152 70 1723.9 14 1.40 2.3% 10.5% net.sources.games
15 4700 1128 4 9.3 0 0.01 2.3% 10.3% mod.newprod
16 4500 1091 25 49.5 5 0.04 2.2% 10.0% net.ai
17 4400 1073 350 767.1 79 0.66 2.2% 9.8% net.micro.pc
18 4400 1055 18 74.5 4 0.06 2.1% 9.6% net.announce.arpa-i
19 4300 1050 350 594.9 81 0.52 2.1% 9.6% net.lang.c
20 4300 1050 41 82.0 9 0.07 2.1% 9.6% net.sources.bugs
21 4200 1016 305 719.1 72 0.64 2.1% 9.3% net.arch
22 4100 1001 394 670.8 96 0.62 2.0% 9.2% net.movies
23 4000 968 90 120.5 22 0.11 2.0% 8.9% net.graphics
24 4000 962 2 3.9 0 0.00 2.0% 8.8% mod.human-nets
25 4000 959 152 222.6 38 0.21 2.0% 8.8% net.consumers
26 4000 958 75 124.3 18 0.12 1.9% 8.8% net.news
27 3900 947 391 762.9 100 0.74 1.9% 8.7% net.micro.mac
28 3800 932 222 329.9 58 0.33 1.9% 8.5% net.cooks
29 3800 925 47 63.5 12 0.06 1.9% 8.5% net.sources.d
30 3700 905 578 980.3 156 1.00 1.8% 8.3% net.music
31 3700 891 1 4.3 0 0.00 1.8% 8.1% mod.os.unix
32 3600 868 420 739.6 116 0.77 1.8% 7.9% net.auto
33 3600 863 397 925.8 110 0.97 1.8% 7.9% net.women
34 3600 861 74 111.4 20 0.12 1.8% 7.9% net.misc
35 3500 853 68 64.6 19 0.07 1.7% 7.8% net.wanted.sources
36 3400 827 110 222.0 32 0.25 1.7% 7.6% net.books
37 3400 820 214 470.8 63 0.52 1.7% 7.5% net.followup
38 3400 817 451 882.3 132 0.98 1.7% 7.5% net.micro.amiga
39 3400 817 35 49.0 10 0.05 1.7% 7.5% net.columbia
40 3400 813 32 43.5 9 0.05 1.7% 7.4% net.jokes.d
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
1 640 155 61 591.8 95 3.50 0.3% 1.4% mod.comp-soc
2 1700 418 478 1021.2 281 2.30 0.9% 3.8% net.philosophy
3 1300 312 177 753.3 136 2.20 0.6% 2.9% net.religion.christ
4 2000 475 215 1068.8 107 2.00 1.0% 4.3% net.micro.atari16
5 2200 533 378 969.5 172 1.70 1.1% 4.9% net.politics
6 880 213 160 407.4 181 1.70 0.4% 1.9% net.politics.theory
7 4800 1152 70 1723.9 14 1.40 2.3% 10.5% net.sources.games
8 5300 1293 985 1665.1 185 1.20 2.6% 11.8% net.singles
9 1800 438 280 572.6 155 1.20 0.9% 4.0% net.comics
10 3200 786 541 970.6 169 1.10 1.6% 7.2% net.sf-lovers
11 1600 386 140 465.2 87 1.10 0.8% 3.5% net.religion
12 1400 346 211 412.4 151 1.10 0.7% 3.2% net.tv.drwho
13 1300 318 201 375.7 154 1.10 0.6% 2.9% net.nlang.india
14 3700 905 578 980.3 156 1.00 1.8% 8.3% net.music
15 3400 817 451 882.3 132 0.98 1.7% 7.5% net.micro.amiga
16 3600 863 397 925.8 110 0.97 1.8% 7.9% net.women
17 3300 809 54 806.3 16 0.92 1.6% 7.4% net.sources.mac
18 6600 1604 47 1481.3 7 0.84 3.3% 14.7% mod.sources
19 1400 331 130 293.5 92 0.79 0.7% 3.0% net.sport.hoops
20 3600 868 420 739.6 116 0.77 1.8% 7.9% net.auto
21 1300 311 15 267.3 12 0.77 0.6% 2.8% mod.politics.arms-d
22 1400 341 92 283.1 66 0.76 0.7% 3.1% net.origins
23 1800 439 154 359.8 85 0.75 0.9% 4.0% net.games.frp
24 3900 947 391 762.9 100 0.74 1.9% 8.7% net.micro.mac
25 1700 413 104 323.3 61 0.72 0.8% 3.8% net.abortion
26 8100 1967 182 1524.7 22 0.71 4.0% 18.0% net.sources
27 1700 416 130 313.8 76 0.69 0.8% 3.8% net.ham-radio
28 4400 1073 350 767.1 79 0.66 2.2% 9.8% net.micro.pc
29 2300 569 214 404.8 93 0.66 1.2% 5.2% net.video
30 4200 1016 305 719.1 72 0.64 2.1% 9.3% net.arch
31 2700 653 145 450.8 53 0.63 1.3% 6.0% net.sci
32 4100 1001 394 670.8 96 0.62 2.0% 9.2% net.movies
33 2900 713 20 480.2 6 0.62 1.5% 6.5% mod.newslists
34 2000 481 197 331.4 98 0.62 1.0% 4.4% net.pets
35 1400 337 5 212.7 4 0.57 0.7% 3.1% mod.mag.otherrealms
36 510 124 52 75.9 103 0.56 0.3% 1.1% net.music.makers
37 1400 344 127 199.6 90 0.54 0.7% 3.1% net.sport.baseball
38 4300 1050 350 594.9 81 0.52 2.1% 9.6% net.lang.c
39 3400 820 214 470.8 63 0.52 1.7% 7.5% net.followup
40 2500 598 132 327.4 53 0.49 1.2% 5.5% net.kids
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 1700 418 478 1021.2 281 2.30 0.9% 3.8% net.philosophy
2 5300 1293 985 1665.1 185 1.20 2.6% 11.8% net.singles
3 880 213 160 407.4 181 1.70 0.4% 1.9% net.politics.theory
4 2200 533 378 969.5 172 1.70 1.1% 4.9% net.politics
5 3200 786 541 970.6 169 1.10 1.6% 7.2% net.sf-lovers
6 3700 905 578 980.3 156 1.00 1.8% 8.3% net.music
7 1800 438 280 572.6 155 1.20 0.9% 4.0% net.comics
8 1300 318 201 375.7 154 1.10 0.6% 2.9% net.nlang.india
9 1400 346 211 412.4 151 1.10 0.7% 3.2% net.tv.drwho
10 1300 312 177 753.3 136 2.20 0.6% 2.9% net.religion.christ
11 3400 817 451 882.3 132 0.98 1.7% 7.5% net.micro.amiga
12 3600 868 420 739.6 116 0.77 1.8% 7.9% net.auto
13 3600 863 397 925.8 110 0.97 1.8% 7.9% net.women
14 2000 475 215 1068.8 107 2.00 1.0% 4.3% net.micro.atari16
15 510 124 52 75.9 103 0.56 0.3% 1.1% net.music.makers
16 3900 947 391 762.9 100 0.74 1.9% 8.7% net.micro.mac
17 2000 481 197 331.4 98 0.62 1.0% 4.4% net.pets
18 4100 1001 394 670.8 96 0.62 2.0% 9.2% net.movies
19 2500 594 238 308.5 95 0.46 1.2% 5.4% net.games.hack
20 640 155 61 591.8 95 3.50 0.3% 1.4% mod.comp-soc
21 2300 569 214 404.8 93 0.66 1.2% 5.2% net.video
22 1400 331 130 293.5 92 0.79 0.7% 3.0% net.sport.hoops
23 1400 344 127 199.6 90 0.54 0.7% 3.1% net.sport.baseball
24 1600 386 140 465.2 87 1.10 0.8% 3.5% net.religion
25 1800 439 154 359.8 85 0.75 0.9% 4.0% net.games.frp
26 2500 603 205 295.6 82 0.44 1.2% 5.5% net.startrek
27 4300 1050 350 594.9 81 0.52 2.1% 9.6% net.lang.c
28 4400 1073 350 767.1 79 0.66 2.2% 9.8% net.micro.pc
29 1700 416 130 313.8 76 0.69 0.8% 3.8% net.ham-radio
30 4200 1016 305 719.1 72 0.64 2.1% 9.3% net.arch
31 1800 437 127 177.1 70 0.37 0.9% 4.0% net.consumers.house
32 2700 648 188 280.9 69 0.39 1.3% 5.9% mod.computers.vax
33 5300 1288 358 603.4 67 0.43 2.6% 11.8% net.unix
34 2200 522 148 212.1 67 0.36 1.1% 4.8% net.aviation
35 1400 341 92 283.1 66 0.76 0.7% 3.1% net.origins
36 3400 820 214 470.8 63 0.52 1.7% 7.5% net.followup
37 1100 268 68 106.3 62 0.36 0.5% 2.5% net.test
38 2500 594 152 235.5 61 0.35 1.2% 5.4% net.bicycle
39 1700 413 104 323.3 61 0.72 0.8% 3.8% net.abortion
40 1000 252 60 100.9 60 0.38 0.5% 2.3% net.tv.soaps
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
205 940 228 55 81.1 59 0.32 0.5% 2.1% net.micro.atari8
206 930 226 18 42.0 19 0.17 0.5% 2.1% net.sport.hockey
207 890 215 24 32.5 27 0.14 0.4% 2.0% net.rec.drugs
208 880 213 160 407.4 181 1.70 0.4% 1.9% net.politics.theory
209 840 204 4 3.8 5 0.02 0.4% 1.9% net.micro.ti
210 740 180 21 46.8 28 0.24 0.4% 1.6% mod.computers.massc
211 640 155 61 591.8 95 3.50 0.3% 1.4% mod.comp-soc
212 560 135 1 1.5 2 0.01 0.3% 1.2% mod.announce
213 510 124 52 75.9 103 0.56 0.3% 1.1% net.music.makers
214 480 117 7 33.8 14 0.26 0.2% 1.1% mod.conferences
Valid data received from these sites:
3comvax 3d.dec.com 8702.dec.com aaec able.dec.com acetes adelie adobe
aero aero2 akgua akgub akguc akgud akov68.dec.com alberta alv
amber.dec.com amdahl amdcad amdimage anasaz ant.dec.com aragorn
arran.tcom.stc.co.uk arthur ascvax astrovax atari athena aurora
avanti.dec.com axis bach.dec.com bagels.dec.com bartok.dec.com basser
bdmrrr bek-mc bene beowulf birtch bnl boehm.dec.com boves.dec.com brand
btnix bute.tcom.stc.co.uk cad.dec.com cadomin cae780 caip.rutgers.edu
carmel cascade casto.dec.com cavell cbosgd ccvaxa celica.dec.com
chalmers cheviot chronon circe cit-vax closet.dec.com clt.dec.com cod
cogito.dec.com cogsci.berkeley.edu columbia comet.dec.com
comet2.dec.com cooper cp1 cuae2 curium.dec.com cuuxb cvl cxsea cybvax0
dalcs darth davinci dec-marlboro.arpa decuac decwrl delni.dec.com
desint diablo dicome dione donner.dec.com down dregs.dec.com drexel
dssdev.dec.com edison elsie elwood.dec.com enmasse eros euclid.dec.com
eureka.dec.com exodus.dec.com fai felix felix.dec.com fgvaxu.dec.com
foxvax5 fritz frog frog.nosc.mil gallo.dec.com ganash
garfield.columbia.edu garfield.mun gatech gemvax.dec.com genrad gitpyr
glacier glimmer gold.dec.com gould9 gramps.dec.com greg gsc gt-stratus
gvadg1.dec.com hammer handel harvard hercules ho95e hocad hydra.dec.com
ia-sun2 iapetus icom ihu1n im4u imagen imt3b2 imt3b2 infinet infopro
ink.dec.com iosg.dec.com ipso iscuva ishtar jasper jaws.dec.com jimi
jon.dec.com jplgodo kepler killer kirk.dec.com kodak kosman kpe labrea
lando.dec.com latour.dec.com ll-vlsi lmi-ang lmi-angel logic.dec.com
louie.dec.com lsmvax.dec.com luke lymph.dec.com macbeth masscomp mcc-pp
mcgill- mck-csc meccts medea mentor.dec.com metoo.dec.com micomvax
midacs miles.dec.com mirror mit-eddie mit-trillian mnetor mntgfx
mordred msudoc mtblue.dec.com mtgzy mtgzz mulga munnari myrias navajo
nbires ncoast ncr-sd ncrcae nimbus.dec.com njitcccc noao nonode.dec.com
novavax nttlab nymgr.dec.com oberon oblio.dec.com ocean oddjob ohgua
ohgub ohguc onecom opus orstcs osiris otto panda par5.dec.com parcvax
parrot.dec.com pbsvax.dec.com pegasus percival philabs phoenix phri
phuxa phuxc pitt pldvax.dec.com plooba plus5 pneuma.dec.com pogo popeye
poseidon potomac princeton prism psivax pucc-h pucc-i pucc-j pucc-k
pyramid quad1 quark.dec.com ra rainbo.dec.com raja.dec.com
rangly.dec.com raster raynal.dec.com rayssd reed renko.dec.com ritcv
rivest.dec.com rochester roxie.dec.com rti-sel saber sandia
sanfan.dec.com saturn sauron scicom scribe.dec.com sdcc12 sdcc13 sdcc3
sdcc6 sdcc7 sdcsvax se-sd seismo sems shasta shogun.dec.com sicsten
sigma sjuvax sneaky sneezy spastic spock star.dec.com stat-l stride
stsci styx su-isl suadb sw.dec.com talcott tallis.dec.com teddy tekig5
teklds tesla tflop tilt titan titn tkov58.dec.com tonto.dec.com
topaz.rutgers.edu trco01.dec.com trillian troll.dec.com tucos tulane
turtlevax tut twitch tymix ucsfcgl ugdist uiucuxa uiucuxc uiucuxe
uiucuxf ukma ulowell ultra.dec.com umd-cs umd-ua uncle.dec.com unmvax
usc-obe usc-oberon usrcv1.dec.com ut-sally utah-gr utcs vaxine.dec.com
vaxuum.dec.com vianet viking.dec.com vino.dec.com vlnvax.dec.com voder
vu-vlsi vulcan walldata wang7 wanginst warlok.dec.com watarts watcal
watcgl watdaisy watdcsu watdragon wateng water watlion watmath watmum
watnot watopt watpix watrose watvlsi weitek well wisdom yale yetti
yogi.dec.com zeus
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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 40 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.
There are 1724 different sites in the Path lines of articles that
arrived at decwrl in the last month. There are 5548 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 1724 sites, 90 (5%) are DEC E-net hosts not part of
uucp. The DEC E-net participation in USENET complicates the statistics,
because we have 100% data for readership of USENET inside the DEC-Enet,
which makes extrapolating less accurate.
Despite these various difficulties, I believe that 1724 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 month, 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. I sampled 13 machines recently
and found only 2 users out of 715 who were actually news readers but whose
.newsrc file was not in their root directory. From this I have concluded that
the problem is not worth worrying about, since the error in network size
estimation will totally dominate it.
MESSAGES PER MONTH AND KILOBYTES PER MONTH
Traffic is measured at decwrl. 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 uniform across all newsgroups, and which therefore does not 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 program
works on news 2.9, and 2.10.[1-3]; Rich Salz has a version that works on
some versions of notesfiles.
Brian Reid
DEC Western Research Laboratory, Palo Alto CA
reid@decwrl.DEC.COM
{ihnp4,allegra,decvax,ucbvax,sun,glacier}!decwrl!reid