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the study.
Although the decision to recruit study participants at the central agency may have resulted in
a sample containing smaller numbers of under 16 and over 70 year-olds than could have been selected from the entire clinical population for this agency, inclusion of these age groups may, in the event, be the exception rather than the norm for NHS specialist agencies which are provided as a component of adult psychiatric services.
Once the study sample had been compared with the clinical population from which it derived, the characteristics of the sample, described in Chapter 8 were compared with the characteristics of people with alcohol and drug problems attending treatment agencies elsewhere.
10.2.2 Generalisability of the study sample
The initial sample was 82% of all first time attenders at the study site during the recruitment period and was thought therefore to be a representative sample of this clinic population. The original sample and the ways in which sub-sets of this sample differed from the original were described in detail in Chapter 8.
Comparisons were made between the study sample and other populations of clinic attenders on demographic characteristics: in the study sample, the ratio of men to women in the alcohol group was 3:1 and the ratio of men to women in the heroin group was 4.2:1. The Northern and Yorkshire Substance Misuse Database reported a ratio of 2.6:1 men to women attending agencies for the first time for treatment of alcohol misuse and dependence in the Northern Region (that adjacent to the region of which the study site is part) in the year immediately following the study recruitment period. This ratio was 2.4:1 for the two years preceding and including the year of recruitment in the Northern region and 2.2:1 in the Yorkshire region (Pace 1997). The ratio of men to women attending agencies for the first time for treatment of a drug problem other than alcohol was 3.5:1 in the Northern region and 2.8:1 in the Yorkshire region in the year immediately following the study recruitment period (Pace 1998). The ratio of men to women in the study sample at t1 was slightly higher than that reported for the whole region and the adjacent region but characteristic of the greater proportions of men to women commonly found to attend specialist services. This is likely to be a function of the repeated finding that women drink and take drugs less than men do and experience fewer alcohol and drug problems on all indices than men (Raistrick et al. 1999 ch.5; Edwards 1995 ch.1). Also, women with alcohol problems are thought to underutilise treatment services to a greater extent (Schober and Annis 1996; Walitzer and Connors 1997) and for different reasons (Thom 1986) than do men.
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