Bandura's social cognitive theory 22 proposes that behaviour is determined by incentives (see operant conditioning below) and expectancies. Three kinds of expectancies are described in the theory: situation outcome expectancies, outcome expectancies and self-efficacy expectancies. Situation-outcome expectancies are beliefs about how events are connected (e.g., smoking is bad for your health). Outcome expectancies refer to beliefs about the consequences of performing a behaviour (e.g., if I stop smoking, I will put on weight). Self efficacy expectancies are beliefs about one's ability to perform the behaviour (e.g., I can stop smoking). All of these are seen to be important in health behaviours, but self-efficacy expectancies have been found to be the most important in empirical studies 23. It has been successfully applied to a wide range of health behaviours, and is one of the most powerful and consistent predictors 24. For this reason, we will include the self-efficacy construct as a predictor variable.

The theory of planned behaviour 25 proposes that the strength of an individual's intention (or motivation) to engage in a behaviour, and the degree of control they feel they have over that behaviour (perceived behavioural control) are the proximal determinants of engaging in it. The perceived behavioural control construct in the theory of planned behaviour is closely related to (and originates from) the concept of self-efficacy in social cognitive theory. Recent studies have suggested that it is a broader construct, however, and is a proxy measure of the degree of actual control that people have over their behaviour as well as their confidence in performing it 2627. The theory of planned behaviour also includes propositions about the determinants of intention strength. It proposes that intention strength is determined by three variables: attitudes towards the behaviour, subjective norms and perceived behavioural control over it. These variables in turn are based upon salient beliefs about the behaviour.

Attitudes towards the behaviour are proposed to arise from a combination of beliefs about its consequences (behavioural beliefs – conceptually similar to outcome expectancies in social cognitive theory) and evaluations of those consequences (outcome evaluations). Subjective norms are based on perceptions of the views of other individuals or groups (normative beliefs), and the strength of the individual's desire to gain approval of these groups (motivation to comply). Influential people might include members of the clinical team, senior staff, patients, managers and professional organisations. Perceived behavioural control is a function of beliefs about factors likely to facilitate or inhibit the behaviour (control beliefs). These might include organisational constraints and patient preferences. This theory also proposes that attitude, subjective norm and perceived behavioural control have determinants. The attitude component is a function of people's beliefs about the outcome of the behaviour combined with their evaluation of these outcomes (similar to outcome expectancies in social cognitive theory). The subjective norm component is a function of beliefs about the preferences of other salient groups or individuals, multiplied by the person's motivation to comply with this reference group. Perceived behavioural control is determined by beliefs about the potential barriers and facilitators to performing the behaviour, multiplied by the perceived power of these factors to inhibit or facilitate the behaviour. It is by measuring these beliefs that the theory of planned behaviour becomes sensitive to factors such as patient preferences or resource constraints on health professional practice. The four proximal determinants of behaviour from the theory of planned behaviour will be included as theoretical constructs (i.e., behavioural intention, attitude, subjective norm, perceived behavioural control). Determinants of attitude, subjective norm and perceived behavioural control will also be measured. These will only be included as predictor variables for the behavioural outcomes in the final analysis however if preliminary analysis shows that their effects on behavioural intention are not mediated by attitude, subjective norm and perceived behavioural control respectively.

Operant conditioning proposes that behaviours that have perceived positive consequences for the individual (such as remuneration) are likely to be repeated, whereas those that have perceived unpleasant consequences will become less frequent 28. This is equivalent to the concept of incentives in social cognitive theory. An incentive is a perceived positive consequence of a behaviour. It can take a variety of forms, from material incentives (e.g., financial rewards), through social incentives (e.g., maintaining a positive relationship) to personal incentives (e.g., achieving a desired goal). The principle that positive consequences promote repetition of behaviour is well established and has been widely and successfully used to understand behaviour and behaviour change 29. As rewarded behaviours are repeated, and may become 'habitual', the frequency of past behaviour can be a powerful predictor of future behaviour 30. We will include two theoretical constructs derived from operant conditioning theory: perceived consequences of behaviour and frequency of behaviour in the past.

Gollwitzer 31 has made the distinction between goal intentions' and 'implementation intentions'. A goal intention is an intention to perform a behaviour or achieve a goal (e.g., I intend to reduce the number of referrals I make for lumbar spine x-rays). This is conceptually close to the behavioural intention construct in the theory of planned behaviour. By contrast, 'implementation intentions' are explicit plans about when and where a goal intention will be achieved 31. Gollwitzer argues that by creating an implementation intention, people effectively transfer control of the behaviour to the environment – establishing cues to action. For example, by saying that 'When a patient tells me about their low back pain, I will explain the pros and cons of an x-ray to them'. This is a relatively new concept in health behaviour research, however experimental studies suggest that people who have formulated plans like these are more likely to translate their intentions into action than those who have not 3233. The extent of prior planning will be included as a theoretical construct.

In addition to plans and behavioural consequences, it seems likely that the actions that health professionals take may be influenced by their views and feelings about the particular condition that a patient has presented with. Leventhal's self-regulatory model 34 proposes that individuals attempt to make sense of illness by making use of pre-existing knowledge or schemas (cognitive representations), and that these give rise to behavioural responses. For patients, behavioural responses may include going to see a doctor, taking prescribed or non prescribed medicines, participating in rehabilitation programmes etc. For clinicians, responses may include referring a patient for diagnostic tests, prescribing a drug, restoring a carious tooth etc. The model is described as self-regulatory because this is seen as a dynamic process. The aim of the actions that people take is to restore their own (or their patient's) physical or emotional equilibrium. Individuals monitor the success of the strategies they have adopted to cope with the health threat, and persist with those that enable them to solve the problem of what is happening to their health 34. Such representations have been shown to influence the behaviour of patients, e.g., coping with everyday living 35, taking prescribed medication 36 and attending cardiac rehabilitation programmes 37. In the proposed project we will investigate whether the cognitive representations that health professionals hold of particular conditions and their emotional reactions to them influence the care that they provide. As far as we are aware, the theory has not been used in this way before.

The individual's own understanding (cognitive representation) of their situation is central to the self-regulatory approach. Leventhal and his colleagues have shown that in relation to illness, this representation has five clear components: these are the perceived identity, cause, controllability, duration and consequences of the condition 34. These influence how the individual responds to the problem. In addition to coping with their beliefs about the illness, the self-regulatory theory proposes that people actively try to cope with the emotions that are associated with the illness (e.g., fear or distress). These coping responses are also behavioural, and can include a wide range of activities, from information seeking to smoking. It seems likely that health professionals also experience emotional reactions to some conditions or patient groups, for example the emotional reaction to 'heartsink' patients, which may influence their practice. Hence, we will include six theoretical constructs from self-regulatory theory: perceived identity, cause, controllability, duration and consequences of the condition, and emotional reaction to the condition.

Stage theories propose that behaviour change occurs in a stepwise process, rather than a linear fashion as implied by motivational or action theories. From a stage theory perspective, interventions to facilitate change will be most effective if they are tailored to the stage an individual has reached within this process. Stage theories have been used widely to develop interventions to facilitate changes in behaviours such as smoking cessation (e.g. 38). While there are differences between the stage models in the number and nature of stages proposed, stage theories typically distinguish motivation and action steps 394041. Empirical studies of general population groups have demonstrated that linear or simple two-stage theories (motivation and action) can be as useful as more complex five or seven stage theories for some health-related behaviours 42 and Weinstein et al have demonstrated that different factors influence behaviour at these two stages 43. Further, in the Precaution Adoption Process model, Weinstein has proposed an additional early stage when individuals may be unaware of the need for behaviour change, a stage which may have particular relevance to the early stages of the implementation of evidence 40. We propose to investigate a four stage model (unaware, unmotivated, motivated but not acting, and taking action) which will be compared with linear theories in order to identify which provides the best rationale for the choice of interventions to change practice.

Rationale: Lumbar spine x-rays are of limited diagnostic benefit within primary care settings and are associated with significant ionising radiation dosage 50. Despite this lumbar spine x-rays are the fourth commonest x-ray request from primary care doctors 51 with referrals continuing at the rate of 7 patients per 1000 patients mean list size per year 52. We have recently completed a trial that found that appropriate indications for referral were not identifiable by case note review for the majority of GP requests 52. The trial also observed a reduction in lumbar spine x-rays of 20% without apparent adverse effects following the introduction of educational messages 52.

Dependent variable: Lumbar spine x-ray requests per 1000 patients per year.

Data sources: We will undertake surveys in geographically distinct areas where general medical practitioners refer to a single radiology department. In addition we will only use departments that have a computerised information system storing details of requesting general practitioner and type of x-ray. After obtaining consent from the study practitioners, we will ask the radiology departments to provide data on lumbar spine x-ray requests for three months following the survey. We have successfully used this method in two different studies across six radiological departments 5152.

Rationale: Norethisterone continues to be used widely in the NHS despite evidence of its limited effectiveness and the availability of effective alternatives 53. Almost half a million (497,700) prescriptions were issued in the NHS during 2000.

Dependent variable: Prescriptions for norethisterone per 1000 patients per year.

Data sources: After gaining consent from study practitioners, we will request level 4 PACT data and level 2 SPA data on norethisterone prescriptions. We have successfully used this method in a previous study 54.

Rationale: intra-oral radiographs have been shown to still produce a clinically significant diagnostic yield and to benefit individual patients by allowing better informed treatment decisions 55. Although modern intra-oral dental films are associated with very low doses of ionising radiation, the total national "volume" of radiographs taken is such that exposures are kept as low as is reasonably achievable. Within this context and that of the recently published Selection Criteria in Dental Radiography Guideline 55 however, comparison of data from the English and Scottish Dental Practice Boards 56 has shown that dentists in Scotland are taking fewer than optimal intra-oral radiographs.

Dependent variable: number of intraoral radiographs taken per 100 courses of treatment.

Data sources: Detailed, itemised records of all courses of treatment for NHS patients across Scotland are stored in the MIDAS database at the Dental Practice Board in Edinburgh. This audited information is used for paying dentists and is thus subject to rigorous quality assurance measures.

Rationale: Dental pit and fissure sealants have been shown to be highly effective in preventing dental caries (decay) in the occlusal (biting) surface of posterior teeth 57. Increases in the number of sealants in children aged 6–16 with evidence of pre-existing dental caries would be in accordance with the recommendations of a recent SIGN evidence based clinical Guideline 57.

Dependent variable: mean number of sealants per 6–16 year old child.

Data sources: MIDAS database at the Dental Practice Board in Edinburgh – see Descriptive data below.

Rationale: In recent years it has become evident that the proportion of teeth with significant dental caries involving the dentine which have received restorations is unacceptably low in both primary and permanent teeth 5859. Following the recommendations of a recent SIGN evidence based clinical Guideline 57 would result in an increase in the number of carious teeth restored..

Dependent variable: Mean number of restored teeth per 6–16 year old child.

Data sources: MIDAS database at the Dental Practice Board in Edinburgh – see Descriptive data below.

In the surveys, we will ask respondents to provide personal and professional details that might influence observed levels of behaviour. From general medical practitioners we will seek details of their practice list size, total number of FTE practitioners and whether they work full time or part time. This will enable us to calculate rates corrected for 1000 patients mean list size. We will also ask about respondent's gender in the norethisterone survey as we anticipate that female practitioners are likely to see more female patients than are male practitioners. We will allow for the effects of gender before fitting the predictor variables derived from the psychological theories.

For the General Dental Practitioners we will follow previously successful strategies in securing agreement from the dentists to let us have access to their "dental practice profiles". These are routinely derived and maintained centrally by the Dental Practice Division in Edinburgh (with whom the Dental Health Services Research Unit has secure data links). Profiles show mean values of treatments per month for each dentist against averages for the local Health Board and Scotland as a whole. We will also collect appropriate personal data about the dentists and compare this with data from the recent national "Toothousand" census of General Dentists in Scotland.

The range of included activities will also allow us to explore contrasts between types of behaviour and professional groups. For example, the use of radiography is common in both general medical and dental practice. In addition we have chosen conditions that are clinically important in their own right, and for which evidence-based advice on best practice is available. In order to identify which variables (theoretical constructs) predict practice across these five tracer activities and to incorporate a geographical comparison in general medical practice seven surveys will be required. These will be of:

• General medical practitioners in Scotland to predict prescribing of norethisterone for menorrhagia

• General medical practitioners in England to predict prescribing of norethisterone for menorrhagia

• General medical practitioners in Scotland to predict referrals for lumbar spine x-rays

• General medical practitioners in England to predict referrals for lumbar spine x-rays

• General dental practitioners in Scotland to predict restoration of carious teeth in children

• General dental practitioners in Scotland to predict the use of sealants for the prevention of dental caries

• General dental practitioners in Scotland to predict the use of dental x-rays

Theoretical construct: self-efficacy.

Measures: Two forms of self efficacy have been identified in relation to health behaviours 2260. One is the extent to which people feel competent in general to control the behaviour in question). The other is the extent to which people feel competent to control their behaviour in specific situations. We will use the English translation of the Generalized Self-Efficacy Scale (GSES)61 to measure generalised self-efficacy in relation to the five tracer activities. The range of situations in which the tracer activity occurs, and characteristics of the situation that make the practitioner feel more or less able to control their behaviour will be elicited in the interviews. These interview responses will be used to generate situation specific self efficacy items using item types 61.

Number of items: GSES – 10 items; situation specific self-efficacy – 10–15 items.

Response formats: GSES – four choice response (not at all true – exactly true); situation specific self-efficacy – five point Likert type scales.

Scoring: Total score on GSES (range 10–40); total score for situation-specific self efficacy.

Example questions: 'I am certain that I can restore carious teeth in children'; 'I am confident that I can restore a child's carious tooth, even if the child is very anxious.'

Theoretical constructs: behavioural intentions, perceived behavioural control, attitude and subjective norm.

Measures: The strength of behavioural intentions, perceived behavioural control, attitudes towards the behaviour and subjective norms will be assessed using standard item wordings and response formats 47.

Number of items: 3–5 items per construct.

Response formats: 7 point Likert type scales indicating degree of agreement with the item.

Scoring: Mean score for each construct.

Example questions: 'I feel under social pressure to use dental sealants in the next month' (subjective norm), 'I would like to avoid prescribing norethisterone for patients, but I don't really know if I can' (perceived behavioural control). In addition to these four theoretical constructs, we will measure the strength of beliefs underlying attitude, subjective norm and perceived behavioural control, as specified in the theory of planned behaviour.

The three belief based measures will incorporate the beliefs identified in the interviews but will be assessed using standard item formats. For each of these measures there will be 5–6 belief items matched with 5–6 evaluation items (e.g., 'If I refer a patient for a lumbar x-ray they will be reassured' – a behavioural outcome belief, matched with 'Reassuring patients with low back pain is important' – an evaluation of outcome). Each of these items will be measured on 7 point Likert type scales indicating degree of agreement with the item. Belief item scores will be multiplied with evaluation scores and then combined to form the overall scale.

Theoretical constructs: anticipated consequences of the behaviour; frequency of performing the behaviour in the past.

Measures: The anticipated consequences for the doctor or dentist themselves of performing each tracer activity will be assessed through responses to a series of 'if-then' statements. The range of potential consequences (positive and negative) for each tracer activity will be elicited in the interviews and used to generate items for the questionnaires. The frequency of past behaviour will be assessed by asking the doctor or dentist to estimate how many patients they have seen with tracer condition over a period of time and what proportion they have treated. Number of items: anticipated consequences – 10–15; frequency of past behaviour – 2. Response formats: anticipated consequences – five or seven point Likert type scales indicating degree of agreement with the item; frequency of past behaviour – open questions.

Scoring: anticipated consequences – total score for positive consequences, total score for negative consequences; frequency of past behaviour – proportion of patients treated per number of patients seen in a specified period.

Example questions: Anticipated consequences: 'If I refer a patient for a lumbar spine x-ray, then I will maintain a good relationship with them'; 'If I x-ray a patient's teeth, then the practice will receive a fee'. Frequency of past behaviour: 'Approximately how many patients have you seen with menorrhagia in the last six months?' followed by 'for what proportion of these patients did you prescribe norethisterone?'.

Theoretical constructs: extent of prior planning.

Measures: To date, most studies of implementation intentions have manipulated them in experimental situations, rather than measured them 3233. Hence standard measures of implementation intention have not been developed. We will use one of open questions developed to assess stage of change (see below), but coded to describe the extent of prior planning. Number of items: 1–2 Response formats: open responses.

Scoring: Responses will be coded by two independent coders into three categories: no evidence of a plan, some evidence of planning, and clearly specified plan.

Example questions: 'if you have thought about changing your practice, what have you decided to do?'; 'how will you go about this?' (please describe)

Theoretical constructs: Perceived identity, cause, controllability, duration and consequences of the condition; emotional response to the condition (state anxiety).

Measures: Perceived identity, cause, controllability, duration and consequences of the condition will be assessed using questions derived from the Illness Perception Questionnaire 62. To measure emotional response we will use the state anxiety items from the Spielberger State-Trait Anxiety Inventory 63. We will preface the items by asking the respondents to think about patients with this condition and to answer the questions according to how they feel about them.

Number of items: cognitive representations – 38 items; emotional response – 20 items.

Response formats: identity – the number of symptoms endorsed as being part of the illness from a list of 15 symptoms (score range 0–15); cause, cure/control, duration, consequences – items rated on five point scales from strongly agree to strongly disagree; state anxiety – four choice response (almost never – almost always).

Scoring: Total score for each of the five dimensions of cognitive representation; total score for state anxiety.

Example questions: 'Menorrhagia is a serious condition' (consequences); 'Norethisterone will be effective in curing menorrhagia' (cure/control); 'Low back pain will last a long time' (duration); 'I feel like a failure' (state anxiety).

Theoretical construct: stage of change.

Measures: Questions adopting a similar format to those used in studies using the transtheoretical model of behaviour change or the precaution adoption process model 436465.

Number of items: 4–5 questions.

Response formats: yes/no or open response.

Scoring: Responses will be coded by two independent coders into four categories: unaware, unmotivated, motivated but not acting, and taking action.

Example questions: 'Have you heard about the evidence relating to norethisterone and menorrhagia' (no = unaware), 'if you have heard about this evidence, have you ever thought of changing your practice' (no = unmotivated), 'if you have thought about changing your practice, what have you decided to do?' (responses could include deciding that no action is required, or deciding to change practice in some way); 'if you have decided that you need to change your practice, have you done anything about it? (yes = taking action; no = motivated but not acting).

Measures will be developed for each predictor variable for each survey. We will use existing measures as a starting point in this process (wherever possible), and we will follow the standard procedures that have been described to develop measures of these theoretical constructs (e.g. 66). Initially we will conduct semi-structured interviews with a purposive sample of 10–15 practitioners for each survey. The purpose of these interviews is to identify beliefs and attitudes relevant to the specific tracer activity and its associated health problem. The responses to these questions will be used to generate standard questionnaire items to assess the variables. Each questionnaire will then be piloted for clarity and acceptability to practitioners. The reliability of the measures will be assessed prior to analysis, using Cronbach's alpha to assess internal reliability and confirmatory factor analysis to identify and discard redundant items. The construct validity of the measures will be assessed prior to analysis by examining correlations between predictor variables that are expected to be similar (convergent validity) and dissimilar (discriminant validity). Measures which do not meet minimum criteria for reliability and validity (i.e., r < 0.7) will not be entered into the analysis.