reid@decwrl.UUCP (08/01/86)
USENET READERSHIP SUMMARY REPORT for Jul 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
----------------------------------------------------------------------------
Recent change: the size of the network is now determined by counting the
number of host names seen in the last 6 months. Previously it was determined
by counting the number of host names seen in the previous 30 days. As I
accumulate more data, I will eventually use 12 months as the time base for
this purpose, so that if a host posts only one message a year, it will be
counted. (For more information, read the explanation at the end of this msg)
----------------------------------------------------------------------------
OVERALL SUMMARY:
This Estimated
Sample for entire net
Sites: 392 3700
Fraction reporting: 10.59% 100%
Users with accounts: 54065 510000
Netreaders: 12229 115000
Average readers per site: 31
Percent of users who are netreaders: 22.62%
Average traffic per day (megabytes): 1.491
Average traffic per day (messages): 629
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 24000 2860 40 113.5 1 0.02 5.3% 23.4% net.general
2 23000 2670 542 714.9 23 0.12 4.9% 21.8% net.jokes
3 19000 2199 152 1265.1 8 0.26 4.1% 18.0% net.sources
4 16000 1892 142 302.4 8 0.07 3.5% 15.5% net.jobs
5 15000 1820 57 1885.1 3 0.49 3.4% 14.9% mod.sources
6 13000 1476 245 390.2 18 0.12 2.7% 12.1% net.unix
7 12000 1441 785 1374.7 65 0.45 2.7% 11.8% net.singles
8 12000 1393 128 130.0 10 0.04 2.6% 11.4% net.wanted
9 12000 1365 262 428.0 21 0.14 2.5% 11.2% net.unix-wizards
10 11000 1351 197 453.7 17 0.16 2.5% 11.0% net.micro
11 11000 1308 125 1921.6 11 0.68 2.4% 10.7% net.sources.games
12 11000 1262 14 43.0 1 0.02 2.3% 10.3% mod.newprod
13 11000 1261 27 37.0 2 0.01 2.3% 10.3% net.ai
14 11000 1259 288 448.7 26 0.16 2.3% 10.3% net.audio
15 10000 1217 392 680.8 39 0.27 2.3% 10.0% net.lang.c
16 10000 1212 361 994.9 36 0.39 2.2% 9.9% net.micro.pc
17 10000 1205 161 182.4 16 0.07 2.2% 9.9% net.rumor
18 10000 1198 161 368.7 16 0.14 2.2% 9.8% net.arch
19 10000 1187 42 87.5 4 0.03 2.2% 9.7% net.sources.bugs
20 9900 1163 24 88.2 2 0.03 2.2% 9.5% net.announce.arpa-i
21 9500 1124 364 648.2 38 0.27 2.1% 9.2% net.micro.mac
22 9500 1120 337 507.3 35 0.21 2.1% 9.2% net.movies
23 9300 1092 72 151.5 7 0.06 2.0% 8.9% net.news
24 9100 1073 154 213.5 16 0.09 2.0% 8.8% net.consumers
25 9100 1068 61 173.3 6 0.07 2.0% 8.7% net.sources.d
26 9100 1068 60 100.1 6 0.04 2.0% 8.7% net.graphics
27 8500 1005 1 4.3 0 0.00 1.9% 8.2% mod.os.unix
28 8500 1004 348 842.4 41 0.39 1.9% 8.2% net.women
29 8500 995 241 379.2 28 0.17 1.8% 8.1% net.cooks
30 8400 986 88 88.3 10 0.04 1.8% 8.1% net.wanted.sources
31 8300 981 565 1048.2 68 0.50 1.8% 8.0% net.music
32 8300 976 147 203.4 17 0.10 1.8% 8.0% net.news.group
33 8200 967 60 72.6 7 0.03 1.8% 7.9% net.misc
34 8000 945 2 3.9 0 0.00 1.7% 7.7% mod.human-nets
35 8000 939 448 746.3 56 0.37 1.7% 7.7% net.auto
36 8000 938 31 522.4 3 0.26 1.7% 7.7% net.sources.mac
37 7900 932 95 179.7 12 0.09 1.7% 7.6% net.books
38 7800 920 325 584.3 41 0.29 1.7% 7.5% net.micro.amiga
39 7700 908 41 58.2 5 0.03 1.7% 7.4% net.jokes.d
40 7600 892 72 202.6 9 0.10 1.6% 7.3% net.lang
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 5100 598 277 1849.8 54 1.40 1.1% 4.9% net.micro.atari16
2 2300 273 100 623.2 43 1.10 0.5% 2.2% mod.comp-soc
3 3000 356 162 686.3 54 0.90 0.7% 2.9% net.religion.christ
4 5300 622 491 1145.0 92 0.85 1.2% 5.1% net.politics
5 4100 482 314 731.8 76 0.70 0.9% 3.9% net.philosophy
6 2100 251 140 370.1 66 0.69 0.5% 2.1% net.politics.theory
7 11000 1308 125 1921.6 11 0.68 2.4% 10.7% net.sources.games
8 7300 856 565 1035.2 77 0.56 1.6% 7.0% net.sf-lovers
9 8300 981 565 1048.2 68 0.50 1.8% 8.0% net.music
10 4300 507 281 549.5 65 0.50 0.9% 4.1% net.comics
11 15000 1820 57 1885.1 3 0.49 3.4% 14.9% mod.sources
12 3400 402 124 412.2 36 0.48 0.7% 3.3% net.religion
13 12000 1441 785 1374.7 65 0.45 2.7% 11.8% net.singles
14 3200 382 147 345.6 45 0.42 0.7% 3.1% net.tv.drwho
15 10000 1212 361 994.9 36 0.39 2.2% 9.9% net.micro.pc
16 8500 1004 348 842.4 41 0.39 1.9% 8.2% net.women
17 8000 939 448 746.3 56 0.37 1.7% 7.7% net.auto
18 3400 399 174 318.4 51 0.37 0.7% 3.3% net.sport.baseball
19 3800 445 64 310.8 16 0.32 0.8% 3.6% net.abortion
20 3800 453 127 300.5 33 0.31 0.8% 3.7% net.ham-radio
21 2800 333 12 218.5 4 0.31 0.6% 2.7% mod.politics.arms-d
22 4500 533 194 347.1 43 0.30 1.0% 4.4% net.pets
23 7800 920 325 584.3 41 0.29 1.7% 7.5% net.micro.amiga
24 6200 732 147 439.0 23 0.28 1.4% 6.0% net.sci
25 10000 1217 392 680.8 39 0.27 2.3% 10.0% net.lang.c
26 9500 1124 364 648.2 38 0.27 2.1% 9.2% net.micro.mac
27 3600 423 15 249.1 4 0.27 0.8% 3.5% mod.music
28 19000 2199 152 1265.1 8 0.26 4.1% 18.0% net.sources
29 8000 938 31 522.4 3 0.26 1.7% 7.7% net.sources.mac
30 7500 879 218 490.0 29 0.26 1.6% 7.2% net.followup
31 4800 565 131 321.0 27 0.26 1.0% 4.6% net.motss
32 4100 481 102 274.2 25 0.26 0.9% 3.9% net.games.frp
33 3300 385 138 213.1 41 0.25 0.7% 3.1% net.nlang.india
34 2500 289 90 161.2 36 0.25 0.5% 2.4% net.tv.soaps
35 3300 389 92 198.6 28 0.24 0.7% 3.2% net.music.gdead
36 6400 755 249 380.0 39 0.23 1.4% 6.2% mod.computers.vax
37 3300 384 70 192.8 21 0.23 0.7% 3.1% net.origins
38 5700 671 208 314.9 36 0.22 1.2% 5.5% net.startrek
39 5500 648 170 303.1 30 0.22 1.2% 5.3% net.video
40 4900 578 187 277.4 38 0.22 1.1% 4.7% net.aviation
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 5300 622 491 1145.0 92 0.85 1.2% 5.1% net.politics
2 7300 856 565 1035.2 77 0.56 1.6% 7.0% net.sf-lovers
3 4100 482 314 731.8 76 0.70 0.9% 3.9% net.philosophy
4 8300 981 565 1048.2 68 0.50 1.8% 8.0% net.music
5 2100 251 140 370.1 66 0.69 0.5% 2.1% net.politics.theory
6 12000 1441 785 1374.7 65 0.45 2.7% 11.8% net.singles
7 4300 507 281 549.5 65 0.50 0.9% 4.1% net.comics
8 8000 939 448 746.3 56 0.37 1.7% 7.7% net.auto
9 5100 598 277 1849.8 54 1.40 1.1% 4.9% net.micro.atari16
10 3000 356 162 686.3 54 0.90 0.7% 2.9% net.religion.christ
11 3400 399 174 318.4 51 0.37 0.7% 3.3% net.sport.baseball
12 3200 382 147 345.6 45 0.42 0.7% 3.1% net.tv.drwho
13 4500 533 194 347.1 43 0.30 1.0% 4.4% net.pets
14 2300 273 100 623.2 43 1.10 0.5% 2.2% mod.comp-soc
15 8500 1004 348 842.4 41 0.39 1.9% 8.2% net.women
16 7800 920 325 584.3 41 0.29 1.7% 7.5% net.micro.amiga
17 3300 385 138 213.1 41 0.25 0.7% 3.1% net.nlang.india
18 10000 1217 392 680.8 39 0.27 2.3% 10.0% net.lang.c
19 6400 755 249 380.0 39 0.23 1.4% 6.2% mod.computers.vax
20 9500 1124 364 648.2 38 0.27 2.1% 9.2% net.micro.mac
21 4900 578 187 277.4 38 0.22 1.1% 4.7% net.aviation
22 10000 1212 361 994.9 36 0.39 2.2% 9.9% net.micro.pc
23 5700 671 208 314.9 36 0.22 1.2% 5.5% net.startrek
24 3400 402 124 412.2 36 0.48 0.7% 3.3% net.religion
25 2500 289 90 161.2 36 0.25 0.5% 2.4% net.tv.soaps
26 9500 1120 337 507.3 35 0.21 2.1% 9.2% net.movies
27 3800 453 127 300.5 33 0.31 0.8% 3.7% net.ham-radio
28 5500 648 170 303.1 30 0.22 1.2% 5.3% net.video
29 7500 879 218 490.0 29 0.26 1.6% 7.2% net.followup
30 1500 181 44 71.4 29 0.19 0.3% 1.5% net.music.makers
31 8500 995 241 379.2 28 0.17 1.8% 8.1% net.cooks
32 5700 672 164 212.4 28 0.15 1.2% 5.5% net.games.hack
33 4600 537 132 224.8 28 0.19 1.0% 4.4% mod.protocols.tcp-i
34 3300 389 92 198.6 28 0.24 0.7% 3.2% net.music.gdead
35 4800 565 131 321.0 27 0.26 1.0% 4.6% net.motss
36 2900 341 78 111.9 27 0.15 0.6% 2.8% net.test
37 11000 1259 288 448.7 26 0.16 2.3% 10.3% net.audio
38 4500 534 121 172.4 26 0.15 1.0% 4.4% net.consumers.house
39 5800 677 150 239.8 25 0.16 1.3% 5.5% net.bicycle
40 4100 481 102 274.2 25 0.26 0.9% 3.9% net.games.frp
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
208 2300 273 100 623.2 43 1.10 0.5% 2.2% mod.comp-soc
209 2300 268 15 25.2 6 0.04 0.5% 2.2% net.rec.bridge
210 2200 264 7 7.8 3 0.01 0.5% 2.2% net.rec.skydive
211 2200 262 24 41.7 11 0.07 0.5% 2.1% net.rec.drugs
212 2100 251 140 370.1 66 0.69 0.5% 2.1% net.politics.theory
213 2100 248 1 4.3 0 0.01 0.5% 2.0% net.sport.hockey
214 2000 233 5 5.7 2 0.01 0.4% 1.9% net.micro.ti
215 1600 192 12 29.9 8 0.07 0.4% 1.6% mod.computers.massc
216 1500 181 44 71.4 29 0.19 0.3% 1.5% net.music.makers
217 1500 177 1 7.8 0 0.02 0.3% 1.4% net.nlang.greek
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 ames anasaz ant.dec.com aragorn
argus arran.tcom.stc.co.uk arthur ascvax astrovax atari athena aurora
axis bach.dec.com bartok.dec.com basser bcm5000 bdmrrr bek-mc bene beno
beorn.dec.com beowulf birtch bnl brand brspyr1 btnix bubba
bute.tcom.stc.co.uk cad.dec.com cadomin cae780 caip.rutgers.edu calgary
carmel cascade casto.dec.com castor.dec.com cavell cbosgd ccvaxa
celica.dec.com cgl.ucsf.edu chalmers cheviot chronon ci-dandelion circe
cit-vax clio clt.dec.com cod cogito.dec.com cogsci.berkeley.edu
columbia comet.dec.com comet2.dec.com cooper cortex cory.berkeley.edu
cp1 cuae2 curium.dec.com cuuxb cvl cxsea cybvax0 dalcs darth davinci
dcl-csvax decuac decwrl delni.dec.com desint diablo dicome dione dmcnh
down dregs.dec.com drexel drillsys dssdev.dec.com edison elsie
elwood.dec.com enmasse entropy eros euclid.dec.com exodus.dec.com fai
felix felix.dec.com fgvaxu.dec.com foxvax5 fremen.dec.com fritz frog
frog.nosc.mil 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 hamstr.dec.com
handel hao harvard hercules ho95e hocad hscfvax hudson.dec.com
hydra.dec.com ia-sun2 iapetus ic ichaya icom ihu1n im4u imagen imt3b2
imt3b2 infinet infopro ink.dec.com iosg.dec.com ipso iscuva ishtar
jasper jimi jon.dec.com jplgodo kepler killer kirk.dec.com kodak kosman
kpe labrea lando.dec.com ll-vlsi lmi-ang lmi-angel logic.dec.com
louie.dec.com luke lymph.dec.com macbeth masscomp mcc-pp mcgill-
mck-csc meccts medea mentor.dec.com micomvax midacs miles.dec.com mips
mirror mit-eddie mit-trillian mnetor mntgfx mordred mosaic.dec.com mss
msudoc mtblue.dec.com mtgzy mtgzz mulga munnari myrias navajo nbires
ncoast ncr-sd ncrcae ncsuvx nike njitcccc noao nonode.dec.com novavax
nsc nttlab nymgr.dec.com oblio oblio.dec.com ocean oddjob ohgua ohgub
ohguc onecom opus orion orstcs osiris otto panda par5.dec.com parcvax
pbsvax.dec.com pegasus percival phdvax.dec.com philabs phoenix phri
phuxa phuxc pitt pixar pldvax.dec.com plooba plus5 pneuma.dec.com pogo
popeye poseidon potomac princeton prism psivax pucc-h pucc-i pucc-j
pucc-k pyramid qnda01 quad1 quark.dec.com ra rainbo.dec.com
rangly.dec.com raster rayssd reed renko.dec.com ritcv rivest.dec.com
rlvd rochester roxie.dec.com rti-sel saber sandia saturn sauron scicom
sdcc12 sdcc13 sdcc3 sdcc6 sdcc7 sdcsvax se-sd seismo sems shasta
shogun.dec.com sicsten sigma sjuvax sneaky sneezy snickr.dec.com soma
spastic sphinx spock star.dec.com stat-l stride stsci styx su-isl suadb
talcott tallis.dec.com teddy tekig5 teklds tesla tflop tilt titan titn
tkov58.dec.com tonto.dec.com topaz.rutgers.edu trco01.dec.com
troll.dec.com tuck tucos tulane turtlevax tut twitch tymix ucsfcgl
ugdist uiucuxa uiucuxc uiucuxe uiucuxf ukma ulowell ultra.dec.com
umd-cs umd-ua uncle.dec.com unirot unmvax usc-obe usc-oberon ut-sally
utah-gr utcs vianet 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
------------------------------------------------------------------------------
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. Each month I store the names
of the hosts that are named that month, and for this report I used the past
4 months worth of data.
There are 3646 different sites in the Path lines of articles that
arrived at decwrl in the last 4 months. 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 3646 sites, 74 (2%) 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 3700 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. 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