reid@decwrl.dec.com (Brian Reid) (12/01/88)
USENET READERSHIP SUMMARY REPORT for Nov 88
This is the first article in a monthly posting series from the Network
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 messages that
follow this one show survey data sorted by various criteria.
The newsgroup volume and article counts that I post are often significantly
different from the ones posted by Rick Adams, because he includes the size of
a crossposted article in every group to which it is posted, whereas I charge
that size only to the first-named group.
The complete set of readership data (of which this is a summary) is posted
in news.lists. The software that will let your site participate in the
survey is in comp.sources.d and news.admin
Brian Reid
OVERALL SUMMARY:
This Estimated
Sample for entire net
Sites: 732 11988
Fraction reporting: 6.11% 100%
Users with accounts: 109834 1798000
Netreaders: 24870 407000
Average readers per site: 34
Percent of users who are netreaders: 22.64%
Average traffic per day (megabytes): 4.517
Average traffic per day (messages): 2132
Traffic measurement interval: last 28 days
Readership measurement interval: last 75 days
Sites used to measure propagation: 665
Valid data received from these sites:
3comvax abstl abvax.icd.abnet.com acadch acer acheron acornrc actisb
adelie alberta alembic aleytys alv alva amc-vlsi amdahl amdcad
ames.arc.nasa.gov amun-re amyerg anasaz andrew.cmu.edu apollo apple
aramis.rutgers.edu ardent ariel arisia arnor arran.tcom.stc.co.uk
arrow.garage.att.com arthur.cs.purdue.edu ascvax astroatc asylum ateng
atom atssc attdso axis b11 babbage balaena bandicoot banzai basser
bast.sics.se bbx bcd-dyn bcsfse bdmrrr beno bentley.garage.att.com
beowulf.ucsd.edu bergman.ericsson.se bigboy bio-image bjs black bnlux0
bnr-rsc bonnie.ics.uci.edu brillig.umd.edu broadway brspyr1 brushtail
bsu-cs btnix bu-cs bu-it bu-tyng bucasb bucsb buengc
bute.tcom.stc.co.uk c3engr c3pe cacilj cad.unsw.oz cadomin caelum
caip.rutgers.edu calgary carola cascade catfish catlabs cavell cbterra
cca ccng ccnysci ceetm1 cfisun cg-atla cgcha cgl.ucsf.edu chalmers.se
charlie chemabs cheviot.newcastle.ac.uk chinet chip cimcor cit-vax
cit-vlsi claris clinet clio cloud9 cnt cognos comdesign
concurrent.co.uk condor conexch coplex cord.garage.att.com cortex cos
cosmo cp1 cpro cpsc6b crash credit crete.cs.glasgow.ac.uk crick crin
crocus crpcapso cs-col.columbia.ncr.com cs-vaxa cs.hw.ac.uk
cs.nott.ac.uk csadfa cseg csi csib csm9a csuchico csuf3b csustan
culdev1 cutter cuuxb cvedg cxsea cybvax0 dahlia daisy daitc.daitc.mil
dalcs dandelion darth dasys1 dayton dciem dcl-cs dcrlg1 ddsw1 ddtcg1
decuac decuac.dec.com dell desint devon dhw68k diamond.bbn.com didsgn
dino drd drexel dri1 dri2 dsacg1 dsacg2 dsacg3 dsachg1 dscatl dsinc
dukcds dukeac dukempd dvinci dvlmarv dycom earvax edison edrsys
edsel.garage.att.com egvideo elan elbereth.rutgers.edu electro elrond
elroy elsie encore eneevax.umd.edu enterprise.mtl.u-tokyo.junet entire
entropy.ms.washington.edu eos eplunix erix ernie.berkeley.edu
euler.rutgers.edu execu expya exunido eyeball fantasci far-side fedeva
fermat.rutgers.edu ficc fishnet flab fortune frc frog gaboon
gang-of-four gargoyle.uchicago.edu gatech gauss.rutgers.edu gcm geac
genrad glacier gold gondor.cs.psu.edu gouldnl grand granite
granjon.garage.att.com gray grebyn grian gtisqr gyre.umd.edu hacgate
haddock.ima.isc.com hammer handel hardees.rutgers.edu hardy harrnl
harvisr haven.umd.edu hawaii.cs.glasgow.ac.uk hawkmoon hcx1 helios
hemuli herman hodge homxb hoptoad hou2c hou2d hou2h hou3b houdi houem
hound hounx houtz houxa houxj houxs houxv hqda-ai hscfvax hsi hurratio
husc4 hutch ibiza ico icot.jp ics.uci.edu idsssd igor iitmax ileaf
ima.isc.com imagen inco infoac.rmi.de infofl.rmi.de infohh.rmi.de io
ipso.oz isaak isg300 islabs island itivax itrpe iuvax ivucsb
izimbra.css.gov jarvis.csri jasper jato jclyde jetson ji.berkeley.edu
jimi.cs.unlv.edu joutsen juice juniper kangaroo karhu killer kodak
kolvi korppi kpd ksuvax1.cis.ksu.edu kurki labrea lakesys lamc
leah.albany.edu lehi3b15 leia libove lifia lily limerick lion ll1a
lll-tis lll-winken log-hb logico looking lotus lownlab lsuc lxn lynx
lyra lzaz lzfmd lzfme lznv lzsc lzss lzvlt m2c maccs madnix magic
magnus mas1 math.rutgers.edu maynard mcdchg mcgill-vision mcgp1 mcmi
meccsd media medusa.cs.purdue.edu meepmeep megatek megatest metasoft
metavax mh.nl mimsy.umd.edu mind minnow mipos2.intel.com
mipos3.intel.com miranda mit-eddie mnetor mntgfx moogvax moscom mrspoc
mss mstar mtfmc mtfmi mtgzd mtgzf mtgzg mtgzi mtgzk mtgzm mtgzn mtgzp
mtgzq mtgzt mtgzy mtgzz mtunb mtund mtune mtunf mtung mtunh mtuni mtunj
mtunk mtunn mtuxj mtuxo mtxinu munsell murphy musys myrias n8emr n8ino
nagano nanovx natinst nbifet nbires ncascade ncoast ncr-sd ncrats
ncrcae.columbia.ncr.com ncrcpx ndmath ndsuvax net.bio.net netsys
newton.rutgers.edu nicmad nitro noao novavax ns nth nttta nuchat
nucleus nud nwnexus obie occrsh octopus oddjob odyssee ogccse olgb1
oli-stl olivea oliveb olivee olivej oliven olivey omepd onfcanim ontenv
opus orca orchid orcisi orion.arc.nasa.gov orion.cf.uci.edu oscvax
osiris osiris.sics.se oswego.oswego.edu otishq otter otto owlmnt oxtrap
pacbell packard.garage.att.com panda paris.ics.uci.edu parsely pbhya
pbhyb pbhyc pbhyd pbhye pbhyf pbhyg pcrat pdn pecan pedev pegasus
percival petro phoenix phri pierce.garage.att.com pikes pilot.njin.net
pixar plaid pmafire polya polyof.poly.edu polyslo polyslo.calpoly.edu
popeye poppy portia portnoy poseidon possum potomac potoroo pr1me
princeton prodix psc psuhcx psy.vu.nl pte ptsfa puck pwa-b pwcs
pyr.gatech.edu pyramid pyrman2 pyrnova pyrps5 pyrtech pyrthoth qiclab
qtc quad1 quick.com quokka radio raphel rayssd rayssdb rayssde rducky
re.sics.se redsox reed rel remus.rutgers.edu rencon renoir.berkeley.edu
resrch retix rhesus.primate.wisc.edu rhi rimsho rivm05 rmi rochester
rocky.oswego.edu rolls rose rosevax rti ruby rutgers.rutgers.edu sacred
sandoz sauron.columbia.ncr.com scicom scobee sdcsvax sdn sdti se-sd
serene shade shamash shark shasta shell shire sialis sics.se sigma
sigmast silver sirius.ua.oz sis siva smdvx1.intel.com sneaky softway
solaris soma splut spsd spurge sq ssbell stanton
starfish.convergent.com stcns3 stevie.cs.unlv.edu stiatl stride studsys
suadb sugar sultra suned1 sunybcs sw1e swan.ulowell.edu swatsun swlabs
t9103 tahoe tahoe.unr.edu td2cad teddy tekecs tekgvs teliut teti tgate
thor tiger tlxprs tmsoft tnosoes toccata.rutgers.edu topaz.rutgers.edu
tove.umd.edu toybox trantor.umd.edu trillium ttidca tuck tucos tw13
tybalt.caltech.edu tymix ubvax.ub.com ucbarpa.berkeley.edu ucla-an
ucqais.uc.edu ucsd.ucsd.edu udiego ueda uhnix1 uhnix2.uh.edu uiucuxa
uiucuxc ukecc umd5.umd.edu umix.cc.umich.edu umn-cs unicom unioncs
unix.cis.pittsburgh.edu uokmax uqcspe.oz urpiainen utacs utstat uunet
uw-june uxe uxf van-bc vanuata.cs.glasgow.ac.uk vaxnix videovax.tek.com
violet violet.berkeley.edu viper virgil virginia viusys voder.nsc.com
vrdxhq vsi1 vu-vlsi w3vh wa3wbu wallaby watale watcgl watdaffy watdcsu
watdewey watdonald watdragon watelse water wateuler wathuey watlouie
watmath watmum watopt watscrooge watsol watson watvlsi watyew wb3ffv
well wjvax wombat wp3b01 wright xanth xicom xray yarra yendor yetti
yunccn yunexus zap zaphod zen ziebmef zinn zorch zycad
------------------------------------------------------------------------------
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 comp.sources.d, 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, and thereby be biased. 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).
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 uunet) 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
13 months worth of data.
There are 11468 different sites in the Path lines of articles that
arrived at decwrl in the last 13 months. There are 5018
different sites in the comp.mail.maps data, but comp.mail.maps 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 11468 sites,
87 (0%) are DEC E-net hosts not part of uucp, and
which therefore are not included in the 5018 figure.
Despite these various difficulties, I believe that 11988 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.
PROPAGATION: HOW MANY SITES RECEIVE THIS GROUP AT ALL
This number is the percent of the sites that are even receiving this
newsgroup. The information necessary to compute propagation was not generated
by early versions of the arbitron program, so the "basis" (number of sites)
used to generate the Propagation figure is smaller than the "Sites in this
sample" figure. A site's data will be used to compute propagation if either
(a) it reports zero readers for at least one group, or (b) it is using an
arbitron with an explicit version number that is high enough.
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. Note that this differs from the
statistics posted from uunet every 2 weeks: the uunet data charge a message
equally to every group that it is crossposted to.
CROSSPOSTING PERCENTAGE: WHAT FRACTION OF THE ARTICLES ARE CROSSPOSTED
"Crossposting" means to post the same article simultaneously in more than one
newsgroup. In genuine "news" systems crossposting is implemented with Unix
links and does not increase the storage or transmisison cost, though in some
other systems crossposted articles are unbundled and must be stored and
transmitted separately.
The "crossposting percentage" is the percentage of the articles in this group
that are crossposted to at least one other group. If every article in this
group is crossposted, the percentage will be 100%; if none is crossposted,
then the percentage will be 0%. The crossposting percentage figure does not
take the size of the article into account, only the number of articles.
Crossposting a 50,000-byte article or a 50-byte article both cause the same
tally.
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 and computer costs to transmit this
newsgroup. The rate of $.0025 per kilobyte is the same value used in the
UUNET statistics reported biweekly. It is based on discussions among system
administrators about the true cost of news transmission.
The cost ratio is computed as follows:
$US/month/reader = ($USPerMonthPerSite * numberOfSites) / numberOfReaders
$USPerMonthPersite = KBytesTrafficPerMonth * $USPerKByte * Propagation factor
$USPerKByte = 0.0025
Combining all these gives
$USPerMonthPersite =
KBytesTrafficPerMonth * 0.0025
= KBytesTrafficPerMonth / 400
Therefore:
$US/month/reader =
(KBytesTrafficPerMonth * numberOfSites) / (400 * 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 comp.sources.d along with this report) work on news 2.9, 2.10.[1-3],
2.11, and on many versions of notesfiles.
Brian Reid
DEC Western Research Laboratory, Palo Alto CA
reid@decwrl.DEC.COM
{ihnp4,allegra,decvax,ucbvax,sun,pyramid}!decwrl!reid