2.3. Lo físico
2.3.3. Vistas del terreno
Roger Wilkins
Table 17.1: Smoking rates in Australia, 2001 to 2010—Persons aged 15 years and over (%)
Smoker Daily smoker
Males Females Males Females
2001 25.1 20.3 – – 2002 26.6 20.3 21.7 16.5 2003 25.4 19.5 21.1 15.9 2004 25.4 19.7 20.9 15.9 2005 25.2 19.2 19.9 15.6 2006 23.0 17.9 18.7 14.7 2007 23.4 17.9 19.4 14.9 2008 22.1 16.6 18.4 13.9 2009 21.8 16.2 17.8 13.1 2010 20.9 16.2 17.1 13.5
the probability of being a smoker. The model includes a variety of demographic characteristics, all of which are interacted with a ‘year’ variable to identify the extent to which the probability of smoking associated with the characteristic has changed over the 2001 to 2010 period. For example, the estimate for the ‘15–19’ age dummy of –0.100
indicates that, all else equal, being aged 15 to 19 years on average decreases the probability of being a smoker in 2001 by 10 percentage points com- pared with being aged 30 to 39 years (the refer- ence category). The estimate for this variable inter- acted with year, –0.006, indicates that the annual rate of change in the probability of smoking is on
Figure 17.1: Smoking rates by age group—Males
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0 5 10 15 20 25 30 35 40 45 % Year 15–19 20–24 25–29 30–39 40–49 50–59 60 and over
Figure 17.2: Smoking rates by age group—Females
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0 5 10 15 20 25 30 35 40 45 % Year 15–19 20–24 25–29 30–39 40–49 50–59 60 and over
average 0.6 percentage points less than for the 30 to 39 years age group—that is, holding other char- acteristics constant, the probability of a 15 to 19 year old being a smoker decreased over the 2001 to 2010 period by 5.4 (9 times 0.6) percentage points morethan the decrease for the 30 to 39 years age group. Thus, the model results show that those aged 15 to 19 years experienced a greater decline in smoking rates than those aged 30 to 39 years. While interpretation of the estimates in Table 17.2 is somewhat difficult, our main focus is on whether the interaction term is negative, indicating rela- tively greater decline in smoking among the demo- graphic group, or positive, indicating relatively less decline (or even increase) in smoking among the group. Note that the average annual rate of decline in the probability of smoking for the reference group—female, in a couple with dependent children, aged 30 to 39 years, non-Indigenous
Australian-born, residing in New South Wales, out- side of a major urban area, in the bottom SEIFA decile, with no post-school qualifications and in the top income quintile—is 0.7 percentage points (bottom of first column). This translates to an aver- age decline in the probability of a reference group member being a smoker of 6.3 percentage points over the full 2001 to 2010 period.
The table shows that there are no significant dif- ferences in rates of decline in the probability of smoking by family type, place of birth, Indigenous status and educational attainment. That is, holding other characteristics constant, there is no statisti- cally significant divergence from the 0.7 percent- age point annual rate of decline in smoking by family type, place of birth and Indigenous status or educational attainment. There are also no significant differences by state or territory, with the exception that, holding other traits constant,
Table 17.2: Characteristics associated with the biggest declines in smoking
Characteristic Characteristic interacted with year
Male 0.068 0.000+
Family situation (Reference category: Couple without dependent children)
Couple with dependent children –0.045 0.001+
Lone parent 0.111 0.002+
Single person 0.059 0.001+
Child of couple or lone parent –0.049 0.003+
Age group (Reference category: 30–39)
15–19 –0.100 –0.006 20–24 0.014+ –0.004 25–29 0.012+ 0.000+ 40–49 –0.050 0.004 50–59 –0.138 0.007 60 and over –0.276 0.005
Place of birth and ethnicity (Reference category: Non-Indigenous Australian-born)
Indigenous 0.108 –0.004+
Immigrant from one of the main English-speaking countries 0.002+ 0.001+
Immigrant from other country –0.046 0.002+
State of residence (Reference category: New South Wales)
Victoria 0.013 –0.001+ Queensland 0.000 0.001+ South Australia 0.011+ –0.003+ Western Australia –0.024 0.000+ Tasmania 0.024 0.002+ Northern Territory 0.151 –0.014
Australian Capital Territory –0.035+ 0.001+
Major urban area 0.009+ 0.000+
SEIFA index decile –0.010 0.000+
Educational attainment (Reference category: No post-school qualifications)
Bachelor’s degree or higher –0.124 –0.001+
Other post-school qualification –0.020 –0.001+ Household equivalised income (Reference category: Top quintile)
Bottom quintile 0.017 0.004 2nd quintile 0.020 0.002+ 3rd quintile 0.008+ 0.001+ 4th quintile –0.008+ 0.004 Year –0.007 – Number of observations 115,745
Notes: Estimates are mean marginal effects from probit models of the probability of being a smoker. The population examined is restricted to persons aged 15 years
people living in the Northern Territory had a much greater rate of decrease in the smoking rate than people living in other jurisdictions: the annual rate of decrease was 1.4 percentage points greater, which translates to a 12.6 percentage point greater decrease in the smoking rate. Note however that, in 2001, the Northern Territory had a 15.6 per- centage point higher smoking rate than New South Wales (holding other characteristics con- stant), so that despite the much more rapid decline in the smoking rate, in 2010 it was still predicted to be higher than in New South Wales. Consistent with the graphs presented in Figures 17.1 and 17.2, significant differences in rates of decline in smoking rates by age are evident. Holding other traits constant, the predicted annual rate of decline in the smoking rate (obtained by adding the esti- mate for the age dummy interacted with the ‘year’ variable to the estimate for the uninteracted ‘year’ variable) is 1.3 percentage points for the 15 to 19 age group, 1.1 percentage points for the 20 to 24 age group, 0.7 percentage points for the 25 to 29 and 30 to 39 age groups, 0.3 percentage points for the 40 to 49 age group, zero for the 50 to 59 age group, and 0.2 percentage points for the 60 and over age group. There are also statistically signifi- cant differences in rates of decline in smoking rates by level of household income. Compared with the top income quintile, the rate of decline is signifi- cantly smaller for the bottom quintile. The decline in smoking rates is not significantly different for the second and third quintiles compared with the top quintile, but—somewhat surprisingly—the decline in the smoking rate for the fourth quintile was sig- nificantly less than the decline for the top quintile (and indeed the decline for the fourth quintile was the same as for the bottom quintile).
Quitting and starting smoking
The HILDA Survey data allow us to consider not just smoking rates in each year, but also the individual-level dynamics in smoking behaviour from one year to the next. In particular, we can examine how many people are smokers in one year and are not smokers in the next year—that is, how many quit smoking—and how many people are not smokers in one year and are smokers in the next year—that is, start (or resume) smoking.
Table 17.3: Proportion of persons aged 15 years and over quitting and taking up smoking each year (%)
Quitting Starting
Males Females Males Females
2002 3.1 2.5 4.4 3.7 2003 3.2 3.2 3.1 2.3 2004 3.2 2.3 3.0 2.6 2005 2.9 2.8 3.1 2.1 2006 4.1 3.1 2.3 2.0 2007 3.0 2.1 2.9 2.3 2008 3.4 2.6 2.6 2.0 2009 3.0 2.4 2.5 1.5 2010 3.1 2.7 2.5 1.8
Table 17.4: Persons who quit smoking—Proportion taking up smoking again within three years, by sex and age group (%)
Males Females Persons
15–19 79.5 44.6 65.4 20–24 71.5 50.5 63.0 25–29 46.7 34.3 40.0 30–39 58.8 47.5 53.0 40–49 47.7 51.8 49.7 50–59 51.0 68.1 58.6 60 and over 49.7 43.8 47.2 All ages 56.4 49.1 52.9 Notes: Age groups are for age at time of quitting smoking. Population
comprises people who quit smoking in the 2002 to 2007 period.
Table 17.3 reports the percentage of people aged 15 years and over who stop smoking in each year and the percentage who start smoking in each year. The table shows that, belying the steady and gradual decline in smoking rates, significant num- bers of people stop and start smoking each year. Between 2 and 4 per cent of all people—or 10 to 20 per cent of smokers—quit smoking each year, but only slightly fewer take up smoking each year. There is consequently quite a high degree of ‘flu- idity’ in smoking status. One implication of this finding is that reducing smoking rates is as much about preventing take-up, or resumption, of smoking as it is about encouraging people to quit smoking. Indeed, it appears from Table 17.3 that the decline in smoking rates has been driven by a decline in the proportion of people taking up smoking each year rather than an increase in the proportion quitting each year. There is no trend increase in quit rates between 2002 and 2010 for males or females, but it is clear that take-up rates are on average lower towards the end of the decade than they were at the start of the decade. For example, between 2002 and 2005, annual take-up rates were 3 per cent or higher for males and 2 per cent or higher for females. Between 2008 and 2010, annual take-up rates were 2.6 per cent or lower for males, and 2.0 per cent or lower for females.
To further emphasise the importance of take-up of smoking as a driver of smoking rates, Table 17.4 examines ‘relapse’ into smoking of people who
quit smoking. For people who quit smoking between 2002 and 2007, it presents the proportion who reported being smokers in the three years subsequent to quitting. For example, a person who quit smoking in 2002 (was a smoker in 2001 and not a smoker in 2002) is defined to relapse if observed to be a smoker in 2003, 2004 or 2005. The table shows that rates of relapse are indeed very high. Over all age groups, the rate of relapse is 49.1 per cent for females and 56.4 per cent for males. For males, the rate of relapse is particularly high for young people, at 79.5 per cent of males aged 15 to 19 years who quit smoking and 71.5 per cent of males aged 20 to 24 years who quit smok- ing. As high as the relapse rates presented in Table 17.4 are, it should be noted that they will actually understate relapse, since many people who quit for less than one year will appear to have never stopped smoking, because we only identify smok- ing status at the time of the annual interview.
Conclusion
Considerable progress has been made on reducing smoking rates in the Australian community over recent decades, although naturally there is plenty of room for further improvement. The HILDA Survey data show that over the 2001 to 2010 period, the
biggest gains have been made among younger people. An important finding deriving from the lon- gitudinal structure of the HILDA Survey is that the decline in smoking rates over the last decade has largely come from reductions in take-up rates rather than increases in quit rates. Indeed, the quit rate among smokers does not appear to have increased at all over the decade. Nonetheless, a significant number of people continue to take-up smoking each year, many of whom are ex-smokers. There is therefore still scope for further reductions in smok- ing through reduction in take-up of smoking, even if quit rates were to continue to remain unchanged.
Endnote
1 In 2001, respondents were asked ‘Do you smoke cigarettes or any other tobacco products?’and provided with the response options ‘No, I have never smoked’, ‘No, I have given up smoking’and ‘Yes’. From 2002, the ‘Yes’ response option was disaggregated into the response options ‘Yes, I smoke daily’, ‘Yes, I smoke at least weekly (but not daily)’and ‘Yes, I smoke less often than weekly’. Consequently, the proportion of people who smoke daily is not available in 2001.
Reference
Australian Institute of Health and Welfare (2012)
Australia’s Health 2012, AIHW, Canberra.