International Journal of Epidemiology
©International Epidemiological Association 1996
Vol. 25, No. 5
Printed in Great Britain
HISTORICAL PERSPECTIVE
Making the Dictionary of
Epidemiology
JOHN M LAST
The frontispiece of Caught in the Web of Words,
Elizabeth Murray's affectionate biography of her
grandfather James Murray, shows the great dictionary
maker in his 'Scriptorium'. One can see his rather
bewildered-looking eyes peering over his glasses, his
long white beard, his crumpled coat and the black cap
of his honorary LL.D. (Edinburgh) which kept his bald
head warm. Behind him is the wall of pigeon holes
where he stowed hundreds of thousands of slips of
paper. He wrote by hand on these the text of the New
English Dictionary on Historical Principles, the OED:
all the words in the English language, their meaning,
provenance, and pronunciation. It is awe inspiring to
think that he wrote it all by hand. Modern dictionary
makers have word processors.
It would be presumptuous even to hint at comparison
to Murray, but I can identify with him. My study when
I delivered copy for the 3rd Edition of the Dictionary
of Epidemiology* to Oxford University Press looked,
perhaps smelt, a little like the Scriptorium, and I felt as
Murray looks in that photograph, except for the cap and
a rather shorter beard. Instead of pigeon holes I had
mounds of paper bearing the ideas of epidemiologists
from all over the world. I was surrounded by the books
I had pulled from their shelves and back issues of
journals of epidemiology.
Compiling the Dictionary of Epidemiology has been
the most fun I have ever had with an epidemiological
project. It began with almost subliminal signals as some
of us commiserated with each other about our perplexing terminology and the meaning of the words and
phrases we use. Anita Bahn took the initiative with
the notion that we needed a glossary in which common
terms appeared in contexts that would make their
meaning plain, with reinforcing definitions as necessary. A few of us began to work on this, but very soon
Anita Bahn died. The Executive Committee of the
International Epidemiological Association (IEA) asked
me to continue the work. I altered course: I visualized a
conventional dictionary of our specialized words and
phrases, and this was announced in the International
Journal of Epidemiology.
I knew what pleasure was in store when I had the first
of innumerable letters from Michel Thuriaux. He wrote
from somewhere in the heart of Africa, on an old
typewriter with a faded red ribbon. I would like to
frame those early letters which displayed his considerable erudition. As well as convincing definitions, they
carried apposite quotations from Lewis Carroll's mock
heroic epic, The Hunting of the Snark.
Many others soon joined the team. One of the happiest aspects of preparing and revising the Dictionary
has been the repeated demonstration that concern for
ways to improve the accuracy and precision of our
accounts of our work transcends national boundaries
and political ideologies. The first two contributors in
alphabetical order in the 3rd Edition come from adjoining nations that have been implacably hostile for at
least two generations. The Dictionary demonstrates that
bellicose confrontations and ethnic tensions do not divide epidemiologists into mutually suspicious enclaves.
Like the infectious pathogens we seek to control, our
science does not recognize borders.
How does one begin to compile a dictionary? I
started with a long list of candidate headings, words and
phrases culled from the indexes of textbooks, monographs and journals. The first mailing for the 1st
Edition2 was that long list. It went to about 30 people;
they struck out many of the items I had listed and added
others I had not thought to include. Some correspondents offered definitions, we copied or adapted others
from existing sources, and I composed many more
myself. These provisional definitions were subjected to
the critical comments of a network that soon extended
to all corners of the world and expanded to over a
Department of Epidemiology and Community Medicine, Faculty of
Medicine, 451 Smyth Road, Ottawa, Canada K1H 8M5.
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MAKING THE DICTIONARY OF EPIDEMIOLOGY
TABLE A few of the candidate entries that did not make the cut
1st Edition:
Conditional relations
Conflator
Cross-sectional curve
Cybernetic
Integer programming
2nd Edition:
Balancing equation
Cline
Deme
Event node
Founder effect
3rd Edition:
'Arrowsmith' bias
'Big science'
CD4 T-lymphocyte
Critical time window
Deconfounding
Manifestational variable
Test bias
Test size
Web of causation
Wheel of causation
Indicant
Isolating mechanism
Multiround survey
Ontology
Dyad
Epstein-Barr virus
Fourier transform
Fraud
Weanling
hundred participants. All who made useful suggestions
are on the list of contributors in the front of the 1st
Edition.
Correspondence that accumulated in the course of
preparing the Dictionary occupies several filing cabinet
drawers. It includes debates among argumentative
epidemiologists that took place through me, akin to
'Exchanges' in the New York Review of Books, polite
but acerbic, sometimes devastating demolition of pretensions to wisdom about epidemiological meanings.
Abe Lilienfeld and I spent a pleasant hour or two looking
through the letters back and forth between a well-known
'words and concepts' epidemiologist and an equally
well-known advocate of the 'mathematical formula says
it all' persuasion. We aimed to distill a short paper from
their letters, but alas, Abe died before the project was
more than a gleam in our eyes. However, the letters still
exist and one day I hope to complete that interrupted
task.
After the 1st Edition was published, some readers
offered corrections and suggestions, and I recruited
them to the mailing list. I followed the same process
with the 2nd and 3rd Editions, beginning each by circulating new items and candidate definitions that were
either revisions of the existing ones or newcomers.
Thus a package of ideas grew and was distributed to
interested parties. If reactions from correspondents
were very negative, the offending idea got no further
unless strong support came from others. The Table
shows a few rejected items.
Some definitions have unforgettable origins. Consider
EPIDEMIOLOGY. This is 'The study of the distribution
1099
and determinants of—not disease, but as Joe
Abramson insisted—'health-related states and events'.
The phrase recognizes that good health and risk-taking
behaviour, as well as disease and injury, are worthy
topics for epidemiologists to study. The final clause in
the definition is there because one day early in 1982
Zbigniew Brzezinski and I were driven across the
plains of Bengal to attend the opening ceremonies for a
new rural health centre. Zbigniew argued that it wasn't
enough merely to say 'study', as we had in a draft I had
sent his Warsaw colleague, IEA past President Jan
Kostrzewski; we had to say what epidemiology is for.
The final clause in the definition, '... and the application of this study to control of health problems', is there
because of our conversation during that long drive in a
Volkswagen bus. We agreed that Jerry Morris had said
it best in his classic work, Uses of Epidemiology:*
epidemiology has important purposes that serve to
enhance the human condition, and these should be part
of the definition. Not all epidemiologists agree: the
clause is missing from the definition in the first French
translation.5 Although some assert that epidemiology
is just a science like others, many, perhaps most epidemiologists, agree with Zbigniew Brzezinski and myself. Douglas Weed has discussed the point in several
eloquent and thoughtful essays.6
One challenge has been trying to set boundaries
around epidemiology that do not encroach too far into
other fields but include useful concepts in those fields
that epidemiologists need to understand. Some terms
from the social and behavioural sciences, demography,
biomedical ethics, medical journalism and informatics
appear because most of us believed users, especially
students, would find these expansions helpful (a few
opposed the expansions but the weight of opinion was
too strong to ignore). The feedback has been very
positive: I cannot recall any negative comments on
these forays beyond our usual working boundaries.
INFORMATICS was a challenge; how far should we have
explored the interface of epidemiology with informatics
and computer science? Conflicting signals reached me
and in the end I decided not to go far. There are, after
all, excellent dictionaries of computer science (one of
these, the Penguin, inexplicably fell out of the 3rd
Edition bibliography).
What about the provenance of epidemiological
terms? We have argued back and forth at length about
this. Origins are often elusive. We had to admit defeat
with CASE-CONTROL STUDY. William Augustus Guy7
described the method in 1843, but did not use this term
for it. Nor did Lane-Claypon8 in her report in 1926. The
two Lilienfelds did not identify the first use of the term
in their paper9 a generation later; nor did Philip Cole in
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INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
describing the evolution of the method in Breslow and
Day's book.10 And why is this the most widely used
descriptive term for the method? Though used in limited circles, case-compeer study, case-referent study,
retrospective study, and Feinstein's 'trohoc'—cohort
spelt backwards—have not caught on. RISK FACTOR
slipped unobtrusively into the language, probably
originating among workers in the FRAMINGHAM STUDY,
and has been in general use since the early 1960s. I am
sometimes credited with the ICEBERG PHENOMENON
because 'The Iceberg' is the title of a widely cited
paper," but that was not my title: when he accepted the
final version of the paper, Sir Theodore Fox, then editor
of Lancet, made only one change, the title, though he let
stand my words, 'Completing the clinical picture in
general practice' as a subtitle.
Can we do anything about techniques and concepts
that have no name? Papers reporting a META-ANALYSIS
often have a figure that summarizes the results in
columns of box and whisker plots, with the size of each
box proportional to the numbers studied, the whiskers
showing the confidence limits and a little diamond
shape to show the combined results in relation to the
95% confidence intervals. We have all seen this figure
in many papers but it has no name. Recalling Michel
Thuriaux's early letters I would like to call it a
'BOOJUM'. Another figure, incomprehensible at least to
me when it appears in an article on a meta-analysis,
purports to show PUBLICATION BIAS. It is called a
FUNNEL PLOT, but I cannot see anything remotely
resembling a funnel about its appearance.
The 'potted biographies' that attracted favourable
comment in the 1st and 2nd Editions have gone from
the 3rd. I miss them, but they were always ethnocentric,
and a problem was arising about who among the
recently-deceased merited mention. However, I have
included the names and dates of important dead epidemiologists and others in entries associated with them.
See,
for example, EPIDEMIC
INTELLIGENCE
SERVICE,
HOSPITAL DISCHARGE ABSTRACT SYSTEM and NATURAL
EXPERIMENT. I did not christen FARR'S LAWS OF EPIDEMICS or HILL'S CRITERIA OF CAUSATION but I admit-
ted them with pride and pleasure.
I allowed some luxuries. EPIDEMICS, HISTORY OF,
INEQUALITIES IN HEALTH, REDEFINING THE UNACCEPT-
ABLE, tidbits of seemingly useless information preserved
in remarks about COMMON VEHICLE SPREAD,
'SHOE-
LEATHER' EPIDEMIOLOGY and a few other entries, are my
efforts to introduce comments of the kind that make
Samuel Johnson's Dictionary such fun to read. I plead
guilty also to editorial comments on a few terms that I
and others disapprove. The suggestion to define and
comment on GAY and GENDER came from an irritated
epidemiologist whose first language is not English,
and I added these with alacrity.
I am impressed by the numbers of contributors
outside the English-speaking world. It is easy to
understand why: when they read and write in English,
they need precise and accurate usage and are keen to
guide others who may be equally perplexed.
Despite my rudimentary French, the members of
ADELF (Association des Epidemiologistes de Langue
Franchise) invited me to join them in compiling the
Dictionnaire d'Epidemiologies using the 1st Edition of
the Dictionary of Epidemiology as a guide. It was a
valuable experience: the precision of French enforces
careful wording, and the 2nd and 3rd English Editions
perhaps reflect this in more precise definitions than
some of those in the 1st. There have been other
translations—Spanish, 12 Portuguese, 13 Japanese, 14
Chinese,15 Farsi (Persian),16 Serbo-Croat,17 and (in progress
or planned)—Greek, Russian, Arabic, Bahasi Indonesian
and a new Japanese translation. Then there is Charles
Florey and his colleagues' Epilex,1* a lexicon in most of
the languages of the European Union. I wonder if any
other technical dictionary has been so often translated.
Murray, and the brothers Grimm who compiled the
Deutsches Worterbuch, understood that there is never
an end to the making of a dictionary. I understood that
too when I was correcting the proofs for both the 1st
and 2nd Editions, and again as I fired off a series of
'afterthoughts' that followed delivery of copy for the
3rd Edition. Afterthoughts have followed this work as
aftershocks follow earthquakes. INFORMATION SUPERHIGHWAY, RISK MANAGEMENT, and a clear definition of
MOLECULAR EPIDEMIOLOGY are among the afterthoughts
in the 3rd Edition.
The 3rd Edition is more liberally sprinkled than the
1st and 2nd with citations to sources and articles that
clarify meanings. A common comment19 is that there
ought to have been more citations to guide readers to
the sources, and in principle I agree; but we all wanted
to keep the size of the book, and therefore its price,
within reasonable limits. With a few exceptions, we
eschewed etymologies for the same reason. We had to
say something about the etymology of EPIDEMIC, and
etymologies are useful to explain the distinction
between ACCURACY and PRECISION, the meaning of
VALIDITY, COHORT, and one or two other basic con-
cepts. Jeffrey House, my ever-helpful editor at Oxford
University Press, and I, would have liked more, but it
would have been a costly luxury that many users might
have resented paying extra to see.
A few items fell through the cracks. In the Acknowledgements of the 3rd Edition, I mentioned an annotated copy of
the 2nd Edition that disappeared from my office. I
MAKING THE DICTIONARY OF EPIDEMIOLOGY
thought I had remembered and reconstructed all the
ideas I had scribbled in that purloined book, but on the
very day I received my first copy of the 3rd Edition I
wanted to look up GENOTYPE and PHENOTYPE, and to my
dismay they were not there: my memory of my stolen
notes had been faulty and nobody else had thought to
include these two terms. They are safely in my file for
the 4th Edition, with other ideas that have surfaced
recently. Six months after the 3rd Edition was
published the candidates for the 4th Edition were
ABATEMENT, COCHRANE COLLABORATION, CULTURE,
GENOTYPE, PHENOTYPE, and POPULATION HEALTH. If we
follow the same course as before, there will be many
other new ideas by the time the team begins to prepare
the 4th Edition.
ACKNOWLEDGEMENTS
Many people played a role in the gestation of the
Dictionary, and this paper. Those named in the front of
each Edition shared in creating the Dictionary and
making it a success. I thank the late John Brotherston,
Kerr White, and other IEA Council members for
entrusting the project to me, and Kerr White in
particular for strong support in the early stages of the
Dictionary's life. Preparation of the 1st Edition was
aided by grants from the National Library of Medicine,
the Rockefeller Foundation and the Milbank Memorial
Fund. The Physicians Services Incorporated Foundation (Ontario) and the International Epidemiological
Association provided some support for the 2nd Edition.
The 3rd Edition was produced without external funding
(important sources of intangible support are mentioned
in the Acknowledgements). Valuable comments on this
paper have been made by Joe Abramson, Jeffrey House,
Michel Thuriaux, Kerr White, and Wendy Last.
1101
REFERENCES
' Last J M (ed.). Dictionary of Epidemiology, 3rd Edition. New
York: Oxford University Press, 1995.
2
Last J M (ed.). Dictionary of Epidemiology. New York: Oxford
University Press, 1983.
3
Last J M (ed.). Dictionary of Epidemiology, 2nd Edition. New
York: Oxford University Press, 1987.
4
Morris J N. Uses of Epidemiology. Edinburgh and London:
Livingstone, 1957 (2nd Edn 1964, 3rd Edn 1975).
5
Jammal A, Allard R, Loslier G (eds). Dictionnaire d'Epidimiologie. St Hyacinthe, Quebec, & Paris: Edisem, Maloine,
1988.
6
Weed D L. Epidemiology, the humanities and public health. Am
J Public Health 1995; 85: 914-18.
7
Guy W A. Contributions to a knowledge of the influence of
employments on health. J R Stat Soc 1843; 6: 197-211.
8
Lane-Claypon J E. A further report on cancer of the breast. Rep
Pub Hlth Med Subj 32. London: HMSO, 1926.
9
Lilienfeld A M, Lilienfeld D. A century of case-control
studies—progress. J Chronic Dis 1979; 32: 5-13.
10
Cole P. Introduction. In: Breslow N E, Day N E (eds). Statistical
Methods in Cancer Research, Volume I: The Analysis of
Case-Control Studies. Lyon: IARC, 1980.
" Last J M. The iceberg; completing the clinical picture in general
practice. Lancet 1964; ii: 28-31.
12
Diccionario de Epidemiologia. Translation by Fernando Fontan
Fontan. Barcelona: Salvat Editores, 1989.
13
Translation supervised by the late Prof. L Cayolla da Motta.
14
Translation by Profs Itsuzo Shigamatsu, Hitoshi Kasugai and
Hiroshi Yanagawa. Tokyo: Japanese Public Health
Association, 1984.
15
Translation by Dr Shi Luyuan. Wuhan, 1984.
16
Translation by Prof. Kiumarss Nasseri. Teheran, 1989.
17
Translation by Prof. Zoran Radovanonic. Belgrade, 1991.
18
Epilex; a multilingual lexicon of epidemiological terms.
Compiled by Josep Anto, Francisco Bolumar, Miriam
Debert-Ribeiro, Jacqueline Fabia, Wilhelm Karmaus, John
Last, Franco Merletti, Evert Schouten; editing and program
by Charles du V Florey. Brussells: Commission of the
European Communities (available on computer disk).
19
Kuller L. Review of 3rd Edition in Ann Epidemiol, 1996;
6: 168.