Gr. Webb, A FILTER MODEL TO DESCRIBE BIAS IN OFFICIAL STATISTICS ON ALCOHOL-RELATED INJURIES, Accident analysis and prevention, 27(5), 1995, pp. 687-697
The paper describes a filter model that can be used to explore the pos
sible biases that occur in reporting of alcohol-related injuries. Thes
e biases occur because of loss of data at various stages of injury rep
orting systems. The filter model consists of four levels or incidences
, with a filter between each level. Level 1 is the total incidence of
alcohol-related injuries. Level 2 is the incidence of reported alcohol
-related injuries. Level 3 is the incidence of reported alcohol-relate
d injuries where the contribution of alcohol has been correctly identi
fied. Level 4 consists of official statistics on alcohol-related injur
ies. Between each of these levels is a filtering mechanism that allows
some but not all data to pass through to the next level. The paper de
scribes the nature of data at each level and the mechanisms operating
at each filter to result in progressive loss of data. Estimates are pr
ovided regarding the extent of loss of data at each filter. Suggestion
s are provided for improving the quality of official statistics on alc
ohol-related injuries.