Australia's Gambling Industries - Productivity Commission

data to derive an overall estimate of the shares of commercial gambling accounted
for by the two groups of problem gamblers (table P.8).
Table P.8
Shares of player losses by severe and moderate problem
gamblers
Gambling type Severe share Moderate share Problem gambling
share
% % %
Gaming machines 33.7 8.7 42.3
Wagering 23.5 9.5 33.1
Scratchies 7.8 11.3 19.1
Lotteries 2.1 3.7 5.7
Casino table games 2.5 8.2 10.7
Other commercial 16.5 8.5 25.0
Total 24.8 8.3 33.0
Source: PC National Gambling Survey and table P.6.
Interestingly, the data suggests that severe gamblers account for the bulk of
expenditure by problem gamblers in gaming machines and wagering. They account
for rather less in the remaining gambling forms, where the evidence from both the
prevalence and treatment data suggest gambling problems are much less extreme.
P.6 Standard errors
The Commission’s survey uses a complex design, with a two phase selection
process for asking expenditure and SOGS questions. This means that conventional
standard errors will tend to suggest a higher level of precision than is actually the
case. In order to provide an estimate of the standard errors corrected for the
complex design, the Commission used a re-sampling approach (the ‘bootstrap’).
This involves using a computer to draw many repeated samples from a ‘master’ data
set, replicating all the features of the complex survey design in each replication.
Then the outcomes from the replications provide an idea of the extent to which the
design and sampling variability affect the precision of the estimates.
The Commission undertook a simulation, with 5 000 replications, to examine the
expenditure shares of each of the major gambling modes as above. For each
replication, a weighted average of the expenditure shares across the modes was
calculated, using the weights from table P.6. These weighted averages were then
sorted in ascending order. The 125 th observation in the list of values then represents
the estimate of the lower 2.5% tail of the 95 per cent confidence interval. Other
values from the list represent other significance cutoff points. The confidence
intervals for each of the gambling modes and for the weighted average of gambling
P.16 GAMBLING