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5. GLOSSARY
Confidence interval | A range of values - expressed as a lower and an upper limit - within which the unknown 'true' value of an estimated quantity (such as an average) is expected to fall. Confidence intervals are expressed in terms of specific levels of uncertainty. For example, a 95% confidence interval indicates a 95% probability that the true value will lie within the stated lower and upper limits. |
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Epidemiology | The study of the distribution and determinants of health-related states and events in populations, and the application of this study to control of health problems |
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Incidence | Number of events (suicides) expressed in relation to a population denominator over a specified time interval ( e.g. 10 per 100,000 people aged 20-24 years per annum) |
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Indirect standardisation | Standardisation is the process by which adjustments are made to take account of differences in the age structures of populations. Indirect standardisation is the procedure for adjusting rates in which the specific rates in a standard population are averaged using as weights the distribution of the study population (see standardised mortality ratio) . |
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Population weighted | Adjusted to take account of the proportion of population living in each geographical area |
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Rate | See incidence |
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Standardised mortality ratio ( SMR) | The ratio of actual (or observed) deaths to the expected deaths. The expected deaths are calculated by multiplying the national age- and sex-specific death rate (known as the 'standard population') by the age- and sex-specific population of a study group (defined, for example, by age, sex, occupation, level of area deprivation) . The mean SMR is 100. A value >100 means that there are more deaths than expected: a value <100, that there are fewer deaths than expected. |
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Time/temporal trend | Direction of change ( e.g. in a rate) over time |
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