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Whariki

DRINKING  IN NEW ZEALAND

National Surveys Comparison 1995 & 2000

 

Ruth Habgood, Sally Casswell, Megan Pledger and Krishna Bhatta,  

 

Alcohol & Public Health Research Unit, November 2001

THE SURVEY: METHODOLOGY

This report is based on data collected in two surveys of 4232 (1995) and 5113 (2000) people aged 14-65 years, which took place between September and December 1995 and 2000. The 2000 survey included an additional booster sample of younger people bringing the sample of those aged 14-19 to 1129.

The questionnaire used in the 2000 National Survey was identical to the one used in the 1995 National Survey, except for changes in response categories in the questions relating to drinking locations and additional questions regarding age verification and supply of alcohol asked of younger respondents.

Interviews for both surveys were conducted throughout New Zealand by a staff of trained interviewers, using the Alcohol & Public Health Research Unit’s (APHRU) computer assisted telephone interviewing (CATI) system.

The sample selection was stratified to reflect the New Zealand population on the basis of geographic regions and level of urbanisation. Telephone numbers were selected within each stratum using a random digit dialling method, so that all households would have an equal chance of being called. Within each household one or more persons was randomly selected by the system for an interview. Each telephone number was tried at least ten times in an effort to reach those seldom at home. This allowed the survey to achieve the relatively high response rates of 76% in 1995 and 73% in 2000.

Both the 1995 and 2000 surveys matched the census profiles for their preceding census – taking into account estimates of population change, although overall males were slightly under-represented. The proportion of Maori in the sample was lower than in the New Zealand population and Pacific peoples were also slightly under-represented.

The regions are grouped to provide a match with the four Regional Health Authority regions in place in 1995. Level of urbanisation is divided into metropolitan (Auckland urban area), large cities (Hamilton, Wellington, Christchurch and Dunedin), smaller main urban areas (population 30,000 and over), large towns/secondary urban areas (10,000 to 29,999), small towns/minor urban areas (1,000 to 9,999) and rural areas (less than 1,000).

Measures

Frequency and quantity of alcohol consumption

It was first ascertained whether respondents had consumed any alcoholic beverage in the previous 12 months. Those who had were then asked to report on drinking in specified locations plus any additional locations they used. For each place, they were asked how often they drank there and what they would drink on a typical occasion at that location. This information was then used to estimate the frequency of drinking, the quantity consumed on typical occasions and the annual volume of alcohol consumed (see Appendix C for further details). The quantity consumed on a typical occasion is reported in the text as number of drinks.

Location of drinking

Data collected for different drinking locations allowed for trends in popularity and drinking patterns in different locations to be analysed. In 1995, 15 locations were asked about plus an ‘any other location’ question. In 2000 two locations were added. These were ‘marae’ and ‘special events’ such as festivals, music events or dance parties. This latter category was added in acknowledgement of these becoming increasingly common locations.[1]

Problems from own drinking

The drinkers were asked how many times in the previous 12 months they had experienced each of 15 consequences from their drinking which, for convenience, will be referred to as ‘problems’. These ranged from more minor problems such as hangovers, influences on performance at work and arguments, to more serious consequences such as getting into fights and motor vehicle accidents. The ‘number of problems’ was the summed frequency of reported problems across all 15 items.

Problems from others’ drinking

All persons, including abstainers, were asked how much harmful effect other people’s drinking was having on three areas of their life: home life, friendships and social life, and financial position. Respondents were also asked about four specific consequences of others’ drinking: being involved in a motor vehicle accident that involved someone else’s drinking; being involved in some other type of accident causing injury or major damage that involved someone else’s drinking; being physically assaulted by someone who had been drinking; and being sexually harassed by someone who had been drinking.

Home production of alcohol

Respondents were asked about the home production of beer and spirits.

Frequency of drinking larger amounts and drinking enough to feel drunk

Another question ascertained how often people drank larger amounts of alcohol. Larger amounts were defined as six or more drinks for men and four or more for women. A ‘drink’ was defined as the equivalent of one can or stubbie bottle of beer, one can of ready-to-drink, one largish (140ml) glass of wine, or a double hotel nip of spirits, all of which approximately equate to 15mls of absolute alcohol.

A separate question asked people how often they drank enough to feel drunk.

Concern over own drinking

The drinkers were also asked whether, compared with a year ago, they were drinking more, less, or the same. They were also asked how happy they were with their current level of drinking compared with the level they felt was right for them.

Possible reasons for increased and decreased consumption

Those who said they were drinking more than the year before were offered a list of possible reasons for drinking more and asked to indicate the reasons that applied to them. There was a similar procedure for those drinking less.

Attitudes to alcohol

Respondents were asked their level of agreement or disagreement with a number of attitude statements.

Host Responsibility

Respondents were asked how likely they thought it was that alcohol would be served to those who were drunk in the various locations they drank in. They were also asked how often in the previous 12 months they had seen police visiting the licensed locations where they drank.

Access to alcohol by younger drinkers

Younger drinkers aged 14-19 were asked how often they had bought takeaway alcohol from a variety of outlets. They were also asked how often they had been refused entry or purchase at these locations and at licensed locations where they had had a drink in the previous 12 months. Drinkers under minimum purchase age, those aged 14-17, were asked how often alcohol had been purchased for them by someone else and who supplied them most often.

Age verification practices

Those under 20 were asked how often they had been asked for age identification.

 

Analysis

The data have been analysed using weighted logistic regression for binary variables, weighted general linear models on the log scale for continuous variables and weighted bootstraps for ratios of continuous variables. The differences between 1995 and 2000 commented on in the text were found to be statistically significant at the 5% level. Data in graphs has been subject to logarithmic transformation for the purposes of statistical analysis and is presented in the form of geometric means. The error bars on the graphs represent 95% confidence intervals and give an indication of the variability in the data. This is described more fully in Appendix B. The geometric mean is a good representation of the typical drinker’s behaviour. Averages (arithmetic means) are used in the text and show the influence of changes in extreme values.

Further details on methodology and sample composition can be found in Appendix A. Details of analysis procedures are in Appendix B. Comparisons with data from Statistics New Zealand on alcohol available for consumption are given in Appendix D.

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