Summary In compiling a patient record many facets are subject to errors of measurement. A model is presented which allows individual error‐rates to be estimated for polytomous facets even when the patient's “true” response is not available. The EM algorithm is shown to provide a slow but sure way of obtaining maximum likelihood estimates of the parameters of interest. Some preliminary experience is reported and the limitations of the method are described.

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Objectives-To assess the impact of myocardial infarction on quality of life in four year survivors compared to data from "community norms", and to determine factors associated with a poor quality of life. Design-Cohort study based on the Nottingham heart attack register. Setting-Two district general hospitals serving a defined urban/rural population. Subjects-All patients admitted with acute myocardial infarction during 1992 and alive at a median of four years. Main outcome measures-Short form 36 (SF 36) domain and overall scores.Results-Of 900 patients with an acute myocardial infarction in 1992, there were 476 patients alive and capable of responding to a questionnaire in 1997. The response rate was 424 (89.1%). Compared to age and sex adjusted normative data, patients aged under 65 years exhibited impairment in all eight domains, the largest diVerences being in physical functioning (mean diVerence 20 points), role physical (mean diVerence 23 points), and general health (mean diVerence 19 points). In patients over 65 years mean domain scores were similar to community norms. Multiple regression analysis revealed that impaired quality of life was closely associated with inability to return to work through ill health, a need for coronary revascularisation, the use of anxiolytics, hypnotics or inhalers, the need for two or more angina drugs, a frequency of chest pain one or more times per week, and a Rose dyspnoea score of > 2. Conclusions-The SF 36 provides valuable additional information for the practising clinician. Compared to community norms the greatest impact on quality of life is seen in patients of working age. Impaired quality of life was reported by patients unfit for work, those with angina and dyspnoea, patients with coexistent lung disease, and those with anxiety and sleep disturbances. Improving quality of life after myocardial infarction remains a challenge for physicians. (Heart 1999;81:352-358)