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Show Epidemiological and Statistical Terms* association A term signifying a relationship between two or more events or variables. Events are said to be associated when they occur more frequently together than one would expect by chance. Association does not necessarily imply a casual relationship. Statistical significance testing enables a researcher to determine the likelihood of observing the sample relationship by chance if in fact no association exists in the population that was sampled. The terms "association" and "relationship" are often used interchangeably. causality Relating causes to the effects they produce. Most of epidemiology concerns causality, and several types of causes can be distinguished. A cause is termed "necessary" when a particular variable must always precede an effect. This effect need not be the sole result of the one variable. A cause is termed "sufficient" when a particular variable inevitably initiates or produces an effect. Any given cause may be necessary, sufficient, neither, or both. confidence interval A range within which an estimate is deemed to be close to the actual value being measured. In statistical measurements, estimates cannot be said to be exact matches, but rather are defined in terms of their probability of matching the value of the thing being measured. epidemiology The study of the patterns of determinants and antecedents of disease in human populations. Epidemiology utilizes biology, clinical medicine, and statistics in an effort to understand the etiology (causes) of illness and/or disease. The ultimate goal of the epidemiologist is not merely to identify underlying causes of a disease but to apply findings to disease prevention and health promotion. etiology Cause. A term used by epidemiologists. indicator A quantitative or statistical measure or gauge for monitoring clinical care. precision In statistics, the quality of being sharply defined or stated. One measure of precision is the number of distinguishable alternatives from which a measurement was selected, sometimes indicated by the number of significant digits in the measurement. Precision can be contrasted with accuracy, which is the degree of conformity of a measure to a standard or true value. Often, however, this contrast is not relevant, because the true value is not known. predictive value The statistic generated by dividing the number of true positives by the sum of the true positives and false positives (e.g. the number of cases with truly good care divided by the sum of the cases with truly good care plus those cases classified with good care who did not receive it - i.e., the likelihood that a patient classified as the recipient of good care actually received good care). rate A measure of the intensity of the occurrence of an event. For example, the mortality rate equals the number who die in one year divided by the number at risk of dying. Rates are usually expressed using a standard denominator such as 1,000 or 100,000 persons. Rates may also be expressed as percentages. regression analysis Regression analysis is a tool used by economists and others to estimate the relationships among a dependent variable Y and one (or many) independent variable(s) X. The purpose of regression analysis is the "best fit" data points from a straight line down on an XY graph. relative risk The rate of disease in one group exposed to a particular factor (e.g., a toxic spill) divided by the rate in another group which is not exposed. A relative risk of one (1) indicates that the two groups have the same rate of disease. risk or risk factor Risk is a term used by epidemiologists to quantify the likelihood that something will occur. A risk factor is something which either increases or decreases an individual's risk of developing a disease. However, it does not mean that, if exposed, an individual will definitely contract a particular disease. standard error In statistics, the standard error is defined as the standard deviation of an estimate. That is, multiple measurements of a given value will generally group around the mean (or average) value in a normal distribution. The shape of this distribution is known as the standard error. survey An investigation in which information is systematically collected. A population survey may be conducted by face-to-face inquiry, by self-completed questionnaires, by telephone, by postal service, or in some other way. Each method has its advantages and disadvantages. The degree to which the results may be generalized depends upon the extent to which those surveyed are representative of the entire population. * Excerpts from Glossary of Terms Commonly Used in Health Care. Printed with permission from Academy for Health Services Research and Health Policy, 1801 K Street NW, Suite 701-L, Washington D.C. 20006-1301. 150 Utah's Health: An Annual Review Volume VIII |