reid@decwrl.dec.com (Brian Reid) (01/01/89)
USENET READERSHIP SUMMARY REPORT for Dec 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: 701 11988
Fraction reporting: 5.85% 100%
Users with accounts: 104093 1780000
Netreaders: 23854 407000
Average readers per site: 34
Percent of users who are netreaders: 22.92%
Average traffic per day (megabytes): 4.400
Average traffic per day (messages): 1866
Traffic measurement interval: last 28 days
Readership measurement interval: last 75 days
Sites used to measure propagation: 640
Valid data received from these sites:
3comvax 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 anicon apollo
apple aramis.rutgers.edu ariel arisia arnor arran.tcom.stc.co.uk array
arrow.garage.att.com arthur.cs.purdue.edu ascvax astroatc asylum ateng
atom atssc attdso axis b11 babbage balaena banzai basser bast.sics.se
bbx bcd-dyn bcsfse bdmrrr beno bentley.garage.att.com
bergman.ericsson.se bigboy bjs black bnlux0 bnr-rsc bonnie.ics.uci.edu
brillig.umd.edu broadway brspyr1 bsu-cs 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 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 cit-vax cit-vlsi
claris clinet clio cloud9 cnt cognos coherent comdesign
concurrent.co.uk condor conexch coplex cord.garage.att.com cortex cos
cosmo cp1 cpmain cpsc6b crash credit crete.cs.glasgow.ac.uk crin crocus
crpcapso cs-col.columbia.ncr.com cs-vaxa cs.columbia.edu cs.hw.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.dec.com dell
desint devon dhw68k diamond.bbn.com didsgn dino dptcdc drd drexel
dsacg1 dsacg2 dsacg3 dsachg1 dscatl dsinc 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 eyeball
far-side fedeva fermat.rutgers.edu ficc fishnet flab fortune frc frog
gaboon gang-of-four garfield 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 gt5000
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 heifetz helios hemuli herman
hodge homxb hoptoad hou2c hou2d hou2h hou3b houdi houem hound hounx
houtz houxa houxj houxs houxv hqda-ai hscfvax hsi hurratio hutch ibiza
ico icot.jp ics ics.uci.edu idsssd igor iitmax ileaf ima.isc.com imagen
inco indep1 infoac.rmi.de infofl.rmi.de infohh.rmi.de io isaak 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 karhu killer kimbal 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 maxim mcdchg
mcgill-vision mcgp1 mck-csc mcmi meccsd media medusa.cs.purdue.edu
meepmeep megatek megatest metasoft metavax mh.nl mimsy.umd.edu mind
mipos2.intel.com mipos3.intel.com miranda mit-eddie mnetor mntgfx
moogvax moscom mrspoc mss mstan 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
musys myrias n8emr n8ino nagano nairobi nanovx natinst nbifet nbires
ncoast ncr-sd ncrats ncrcae.columbia.ncr.com ncrcpx ndmath ndsuvax
net.bio.net netsys newton.rutgers.edu nicmad nis nitro novavax ns nth
nttta nuchat nud nwnexus obie occrsh octopus oddjob ogccse oli-stl
olivea oliveb olivee olivej oliven olivey omepd onecom onfcanim ontenv
opus orca orchid orion.arc.nasa.gov orion.cf.uci.edu oscvax osiris
osiris.sics.se oswego.oswego.edu otishq otter otto owlmnt oxtrap oxy
pacbell packard.garage.att.com panda paris.ics.uci.edu parsely pbhya
pbhyb pbhyc pbhyd pbhye pbhyf pbhyg pcrat pdn pecan pedev pegasus
percival phri pierce.garage.att.com pikes pilot.njin.net pixar plaid
pmafire polya polyof.poly.edu polyslo popeye poppy portia portnoy
poseidon potomac 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 raphel rayssd rayssdb rayssde
rducky re.sics.se redsox reed remus.rutgers.edu rencon
renoir.berkeley.edu resrch retix rhesus.primate.wisc.edu rhi rimsho
rivm05 rochester rocky.oswego.edu rolls rose rosevax rti ruby
rutgers.rutgers.edu sactoh0 sandoz sauron.columbia.ncr.com scicom
scobee sdcsvax sdn sdti se-sd sequent serene shamash shapetc shark
shasta shell shire sialis sics.se sigma sigmast silver sirius.ua.oz sis
siva smdvx1.intel.com sneaky softway solaris soma spike splut spsd
spurge sq ssbell starfish.convergent.com stcns3 stevie.cs.unlv.edu
stiatl stride studsys suadb sugar sultra suned1 sunybcs sw1e
swan.ulowell.edu swatsun swlabs t9103 tahoe td2cad teddy tekcsc tekecs
tekgvs teliut teti tgate thor tiger tlxprs tmsoft tnosoes
toccata.rutgers.edu topaz.rutgers.edu tove.umd.edu toybox
trantor.umd.edu tri-x trillium ttidca tuck tucos tw13
tybalt.caltech.edu tymix ubvax.ub.com ucbarpa.berkeley.edu ucqais
ucsd.ucsd.edu udiego ueda ufqtp 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 videovax.tek.com violet
violet.berkeley.edu viper virgil virginia viusys voder.nsc.com vrdxhq
vsi1 vu-vlsi w3vh wa3wbu watale watcgl watdcsu watdragon watelse water
watmath watmum watopt watsol watvlsi watyew wb3ffv well wheaton wjvax
wp3b01 wright xanth xenna xicom xray yendor yetti yunccn yunexus zap
zaphod ziebmef zinn zorch zycad
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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 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 11908 different sites in the Path lines of articles that
arrived at decwrl in the last 13 months. There are
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 11908 sites,
82 (0%) are DEC E-net hosts not part of uucp, and
which therefore are not included in the 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