Surely a lot depends on the characteristic layout of towns and villages
in Iraq. If the main roads are lined with shops and people typically
live in side streets off them strung out in a linear way following the
main routes, then the sampling method makes a lot of sense (although, of
course, it wouldn't in, say, Manhattan). I just went into Google Earth
to try to see. Unfortunately the images are much fuzzier than those of
London (where I can make out my own garden chairs in the satellite
image) but if you check 'populated places' and 'roads' you can get a
broad sense of how things are laid out. It would take much longer than I
gave it to demonstrate that this is indeed the general pattern although
a cursory look suggested that it may be. You can also check 'shops and
services' and I was hoping to see these clustered along the main roads
but didn't have enough time to investigate this properly. Anyway I pass
the suggestion on for what it's worth
Best wishes
Ursula
Ursula Huws
Professor of International Labour Studies
Working Lives Research Institute, London Metropolitan University
and Director of Analytica Social and Economic Research
web: www.analyticaresearch.co.uk
tel: +44 20 7226 8411
fax: +44 20 7226 0813
mobile: +44 7711 3292 67
-----Original Message-----
From: email list for Radical Statistics [mailto:[log in to unmask]]
On Behalf Of John Bibby
Sent: 20 October 2006 14:16
To: [log in to unmask]
Subject: Iraq again
The BBC mentioned a study yesterday that refuted the 600,000 figure on
the
grounds that "houses near main roads were over-represented" (my
paraphrase).
From the Lancet article it does appear that households on SHORT street
near
main roads will have been over-represented. (However, households on main
roads appear not to have been sampled at all.
If "distance from main road" was collected, as it easily could have
been, it
would be possible to attempt some control for this factor.
Has anybody been in touch with the Johns Hopkins people about our
discussion? (I bet they are fed up with it by now!)
========
I was concerned by Triesman's explanation of why the UK government does
not
interest itself with the accuracy of such figures. (see Ted Harding's
earlier email.)
JOHN BIBBY
========== From NZ!: http://www.scoop.co.nz/stories/WO0610/S00436.htm
Lancet Iraq Study Flawed: Death Toll Too High
Friday, 20 October 2006, 10:36 am
Press Release:
Lancet Study Fundamentally Flawed: Death Toll Too High
October 19, 2006 - 1 page -
For immediate release:
Researchers at Oxford University and Royal Holloway, University of
London
have found serious flaws in the survey of Iraqi deaths published last
week
in the Lancet.
Sean Gourley and Professor Neil Johnson of the physics department at
Oxford
University and Professor Michael Spagat of the economics department of
Royal
Holloway, University of London contend that the study's methodology is
fundamentally flawed and will result in an over-estimation of the death
toll
in Iraq.
-> The study suffers from "main street bias" by only surveying houses
that
are located on cross streets next to main roads or on the main road
itself.
However many Iraqi households do not satisfy this strict criterion and
had
no chance of being surveyed.
-> Main street bias inflates casualty estimates since conflict events
such
as car bombs, drive-by shootings artillery strikes on insurgent
positions,
and market place explosions gravitate toward the same neighborhood types
that the researchers surveyed.
-> This obvious selection bias would not matter if you were conducting a
simple survey on immunisation rates for which the methodology was
designed.
-> In short, the closer you are to a main road, the more likely you are
to
die in violent activity. So if researchers only count people living
close to
a main road then it comes as no surprise they will over count the dead.
During email discussions between the Oxford-Royal Holloway team and the
Johns Hopkins team conducted through a reporter for Science, for an
article
to be published October 20, it became clear that the authors of the
study
had not implemented a clear, well-defined and justifiable methodology.
The
Oxford-Royal Holloway team therefore believes that the scientific
community
should now re-analyze this study in depth.
The team can be reached for comment at;
Gourley: s.gourley1 @ physics.ox.ac.uk mobile:+44 (0) 7733113558
Johnson: n.johnson @ physics.ox.ac.uk
Spagat: M.Spagat @ rhul.ac.uk
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