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CONTENTS
Glossary
Executive
Summary
References
Appendices
A.
Figures
B.
Basic Tables
Glossary
Akaike's
Information Criterion (AIC): Akaike's Information Criterion
is an index for assessing the fitness (as reflected by small
deviation from the observed or large likelihood) of a model,
taking into account the number of parameters in the model.
APHEA:
Air Pollution on Health: a European Approach. This is a research
organization formed by researchers from several European countries,
to study the short term effects of air pollution on health
according to guidelines from an established protocol. The
protocol has been adopted by researchers in Hong Kong.
Collinearity:
An effect due to some strong relationship between pollutants
and/or other covariates when studying their effect on an outcome
such as hospital admissions and deaths.
Covariates:
Variables which are possibly predictive of the outcome under
study. A covariate may be of direct interest to the study,
a confounding variable, or an effect modifier.
95% confidence
interval: An estimate in terms of an interval which has 95%
of the chance to include the true value.
Confounding:
A situation in which the effects of two processes are not
separated. The distortion of the apparent effect of an exposure
on risk brought about by the association with other factors
that can influence the outcome.
Co-pollutant:
A pollutant which coexists with the main pollutant under study.
Estimate:
A measurement or a statement about the value of some quantity
is said to be an estimate if it is known, believed, or suspected
to incorporate some degree of error.
Exposure:
Proximity to and/or contact with a source of a health hazard
(e.g. air pollutants) in such a manner that effective transmission
of the agent or harmful effects of the agent may occur.
FSP: Fine
suspended particulates.
International
Classification of Diseases (ICD): The classification of specific
of conditions determined by an internationally representative
group of experts who advise the World Health Organisation.
The different groups of diseases are subdivided into different
sections or rubrics with unique code numbers.
IPAS:
Integrated Patient Administration System. It was established
by the Hospital Authority for management and retrieval of
hospital patient records. It was being gradually phased out
and replaced by the Medical Record Abstracting System (MRAS).
Lag effect:
Effect due to pollutants and covariates which have occurred
in previous days.
Linear
relationship: A relationship between exposure levels and a
health outcome (or a transformation of it) which can be represented
by a straight line.
ug/m3:
Unit for measuring air pollutant concentration in micro grams
per cubic metre.
um: Micrometre
or micron; one millionth of a metre.
MRAS:
Medical Record Abstracting System. This system was developed
to replace the IPAS system for management and retrieval of
hospital patient records.
p-value:
Probability value; the probability that a test statistic would
be as extreme as, or more extreme, than that observed, if
the null hypothesis were true.
Poisson
regression: A regression method which models counts of events,
which occurred at some point in time, as the outcome variable
and relates them (in this study) to some pollutants and covariates.
Relative
risk: The ratio of the risk of disease or death among the
exposed to the risk among the unexposed.
Risk:
The probability that an event (e.g. admission to hospital
or death) will occur.
RSP: Respirable
suspended particulates.
Time-series
analysis: An approach to estimate acute health effects of
air pollution by statistical modelling of daily counts of
a health outcome on daily average air pollutant concentrations.
The analysis is usually done on a series of several years
of data including hospital admissions, air pollutant concentrations,
meteorological conditions, holidays, day after holidays and
other cyclical factors.
Wave length:
The duration for each seasonal cycle in the health outcome
under study.
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