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4.1 An overview of the studies conducted and samples recruited for the purpose of the present thesis
A test of the readability of the LDQ was conducted and is reported in section 4.2 of the present chapter. Three studies were conducted in preparation for the main study, two for the purpose of further investigating the psychometric properties of the LDQ and one for the adaptation and validation of main study instruments. These preliminary studies and the samples used in them are outlined below and reference made to the chapters in which they are fully described.
i) Response choices in self completion instruments were explored and a small scale study was conducted into the meaning and appropriateness of the response choices in the LDQ. This study is referred to as Study 1 (LDQ response choices) and is described in section 4.3 below.
ii) A further small scale study was conducted to examine the ability of the LDQ to measure dependence in abstinent respondents. Referred to as Study 2 (LDQ abstinence), it is described in section 4.4 below.
iii) Study 3 (adaptation and validation) was the adaptation and validation of two instruments used in the main study. The Impaired Control Scale (ICS) and the Coping Behaviours Inventory (CBI) were originally developed and validated for use with clinic populations of problem drinkers. Versions suitable for use with clinic populations of heroin users were required for the present main study. Study 3 consisted of four parts using four different samples: one for the generation of items to be used in the adapted version of the CBI (the CBIdrg), one for the checking of adapted items in the adapted version of the ICS (the ICSdrg) the third was for validation of both the adapted scales and the fourth was for the purpose of examining the reliability of the instruments. In the fourth part of Study 3, the reliability of an additional instrument, the Social Satisfaction Questionnaire (SSQ), used in the main study was also tested. The development and validation of the original ICS, adaptation, validation and reliability of versions for use in the heroin group in the present main study are described in Chapter 5. Development and validation of the original CBI, adaptation, validation and reliability of versions for use in the heroin group in the present main study are described in Chapter 6. Reliability of the SSQ is reported in Chapter 7.
iv) Study 4 (main study) is reported in Chapters 7, 8 and 9.
Unless otherwise stated, samples were recruited to the studies at the Leeds Addiction Unit, a National Health Service specialist addiction clinic offering treatment of substance dependence and related problems on an out-patient and community basis. The majority of patients referred to the agency report problems with alcohol (37.4% during the study period) and heroin (53.3% of all
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