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Disease Detecitves
SO Disease Detectives
Terms | Definition |
---|---|
Adjusted Measures | Rates or Relative Risk- Effects of differences in the distribution of cofounders in the groups to be compared have been minimised by using special statistical techniques |
Confounders | Variable factors- age, smoking habits |
Analytical Study | A study designed to test a hypothesis. Generally to examine whether a certain exposure is a risk factor for a particular disease |
Attributable Risk | How much greater the frequency of disease is in the exposed group compared to the unexposed. The risk of disease in the exposed group considered attributable tot he exposure. It indicates the number of cases that could be prevented. |
Attributable Risk Fraction | The proportion of disease amoung the exposed that is attributable to the exposure. |
Baseline Data | Data collected at the start of a study to ensure thta the groups to be compared are similar, the only difference being the exposure being studied. |
Case | The individual in a population who has the disease, health disorder or suffers the event of interest. |
Case Control Study | An observatoinal study that starts with the id of a group of case. The level of exposure is measured in the 2 groups & compared. |
Case Fatality Rate | The proportion of cases of a specified condition which are fatal (deadly)within a specified period of time. |
Clinical Trial | An intrevention study in which the unit of allocation to the different group individual patient. |
Cluster Randomised Trial | Trial i which the unit of allocatoin to the different groups is the individual patient. The allocation of the patients may or may not be determined by the radomisation. |
Cohort Study | Follow-Up or Longitudinal STudy - A group of exposed & unexplosed to a risk factor are followed in time & the incidence of the outcome is compared |
Community Trial | Tria in which the unit of allocation is an entire community. The allocation may or may not be determined by randomisation |
Compliance Rate | The proportion of persons who co-operate fullt with all the study procedures. |
Confounders | A situation in which an estimate of the association between an exposure & a disease is distorted because of the association of the exposure with another factor that influences the disease under study. |
Control | An individual who did not recieve the interevention, exposure, disease under study. |
Crossover Trial | A type of CLinical Trial in which each participant acts as their own control, by recieveing at least 2 different treatments at different times. |
Cross Section Study | A study in which information on the putative risk factors & outcomes are measure simutaneously at one point in time. |
Crude Rate | The rate in the total populaiton as a whole. ex. death rate in the general population during the study time. |
Denominator | The lower portion of a fraction used to calculate a ratio |
Descriptive Study | A study designed only to describe the existing distribution of variables in a populaiton without regard to casual or other hypothesis. |
Double Blind Trial | A trial in which neither the participant or the observer knows which treatment the participants have received. |
Ecological Bias | Bias from an ecological studt are extrapolated to individuals. |
Ecological Study | Aggregate Risk Study- A study in which Units of analysis are populations of groups of people rather than individuals. |
Effect Modifier | A factor that modifies the effect of the putative causal factor under study. Variation in effect measure across levels of a 3rd variable. |
Effectiveness | The extent to which an intervention does what it is intended to do when it is applied through a routine delivery system. Hence effectiveness trials. |
Efficacy | The extent to which an intervention does what it is intended to do under ideal conditions. |
Efficiency | The extent to which the effects or end results of an intervention are achieved in relation tot he effort expended in terms of money, resources & time. |
Epidemic | The occurance in a specified, geographically defined populaiton group of an illness, specific health related behavior or other health related event sharply & significantly in excess of what is normally expected for that group |
Epidemiology | Study if distribution& determinates of health related states or events in specified populations, & application of this study control of health problems. Who gets what disease, where, how often & why. |
Evidence Based Medicine | Application of the best evidence in setting public health policies & practices. the evidence may be derived from epidiologic, demographic, sociologic, & economic sources. |
Experimental Group | A study in which conditions are under the direct control of the investigator. The investigator devided people in either an experimental group or a comparison group |
Exposed | The group of individuals who have been exposed to a putative cause of disease or condition of interest, or possess a characteristic that is a determinat of the outcome of interest. |
Exposure response Relatoinship | A relationship in which a change in amount, intensity or duration of exposure is associated with a change- either an increase or decrease |
Field Trial | Atrial in which the participants are not patients, but members of the genreal popoulation. The allocation of the participants may or may not be determined by radomisation |
Generalisability | The extent to which finding are applicable to populations other than that studied |
Health Worker Effect | A type of selection bias in occupational cohorts, the general population is used as the comparison group. Workers tend to have lower overall morboidity & mortality rates than the general population because poeple in employment are healthier. |
Historical Cohort Study | Retrospective Cohort Study- A type of cohort study that relies on data collected in the past. Existing records about the exposure of individuals some time in the past are used to reconsctruct the cohort of exposed & unexposed individual |
Hypothesis | A supposition which is phrased in such a way as to allow it to be tested & confirmed or refuted. |
Incidence | The number of cases of disease that develope in a population of individuals at risk during a specific time interval. |
Incidence Rate | A measure of disease frequency that is obtained by dividing the number of new cases of disease that occur in a populaiton in a given time period by the total person - Time at risk |
Informed Consent | Voluntary consent to be a participant in a study after being informed of its purpose, methods, procedures & potentioal benefits & risks. |
Inter Observer Error | The degree of disagreement between 2 or more observers results of the same measurement on the same individual. |
Intervention | The preventive or therapeutic measure unders tudy in an interventoin study. |
Intervention Group | In an Intervention Study, hte group who is deliberately assigned to receive the intervention. |
Intervention Study | An experimental study designed to test a hypothesis that there is a casual relationship between 2 variables, by modifying the putative casual factor in the population & observing the effect on the outcome. |
Intra Observer Error | The degree of disagreement between repeated observatoins by the same observer. |
Matching | A technique used to adjust for the effects of confounding. COntrols are selected so the distribution is identical to tht amoung cases. Matched by single case or groups. |
Measurement Bias | Occurs when there is a systematic error in measurement or classification of the participants in a study |
Meta Analysis | A statistical synthesis of hte data from seperate but similar studies, leading to a quantitative summary of the pooled results. |
Misclassification | The erroneous classification of an individual, value or an attribute into a category other that that to which it should be assigned. The probability of misclassification may be the same in all study groups. |
Nested Case Control Study | A case-control study in which cases & controls are drawn from the population in acohort study. |
Nonexposed | The group of individuals who were not exposed to the risk factor of a disease or who do not possess the charactreistics that is is a determinant of the outcome of interest. |
Number Neded to Teat | A calculation that enables you to assedd how many people would you need to treat compared to the control in order to improve the specified outcome of 1 person. |
Number Neded to Harm | Assess how many people would need to be exposed to the risk factor of interest in order for 1 person to be harmed with the outcome of interest. |
ObservationStudy | Study in which the role of investigator is an observer of what happen. |
Observer Bias | A type of measurement bias that occurs when data gathering by the investigator is influenced by their knowledge of the exposure (disease) staatus of the patient. |
Odds of Disease | The ratio of the probability of getting the disease to the probability of not getting the disease during a given time period. |
Odds of Exposure | The ratio of probability of having been exposed to a particular risk factor to the probability of not having been exposed. |
Odds Ratio | Odds of Disease or Exposure divided by the odds in the control |
Outcome | A possible result that may stem from exposure to a causal factor or from preventive or therapeutic interventions. |
Person Time | A measurement combining number of people & time observed, used as a denominator to calculate risks. It represents the sum of each individuals timea t risk. |
Preiod Prevalence | The total number of personswho had the disease or health event at any itme during a specified period, taken as a proportion of the total numbre of people in that populaiton during that time. |
Pilot study | A smal scale study of thh e full set of study methods & procedures which will be used on a large scal if hte pilot study demonstrates that they can work. |
Placebo | An inert medication or procedure. Can be given to a control group. |
Point Prevalence | The number o fcases of disease in a populaiton at 1 point in time, taken as a proportion of hte total number of people in that populaiton at the same time. |
population Attributable Fraction | The proportion of disease in the study population that is attributable to the exposure. What fraction of disese could be eliminated if exposure were eliminated? |
Population Attributable Risk | An estimate of the excess risk of disease in th total study population of exposed & unexposed people attributable to the exposure. What is the incidence of disease in a populaiton which is associated witht the occurance of the risk factor? |
Prevalence Ratio | A measure of the strength of an association. The ratio of the prevalence of the outcome or interest in those exposed to the putative risk factor to the prevalence in the unexposed. |
Proportion | A ratio,the numerator is included in the denominator |
Prospective Study | Study in which data are collected in an ongoing way during the study, or that looks forward from exposure to disease. |
Randomisation | Allocation of individuals to groups is determined by chance. All individuals have the same probability of being allocated either to the experiment or to the control group. |
Random Error | Variation of an observed value from the true populaiton value due to chance alone. |
Randome Sample | A group of participants thta was selected from the general population in a randome manner. |
Randomised Clinical Trial | An experimental study in which participants are rendomly allocated to recieve or not the intervention |
Rate | A special type of ratio in which the denominator is expressed in units of Person-Time at risk |
Rate Difference | A measurement of attributable risk. I ti s the absolute difference in incidence rate between a group of individuals exposed to a potentioal risk factor & a group of individuals not exposed. |
Ratio | The value that is obtained by dividing 1 quantity by another. |
Rate Ratio | A type of measure of relative risk. It is the ratio of the incidence rate in the exposed group to the incidence rate in the unexposed group. |
Recall Bias | A type of measurement bias were the ability to remember events in the past is not independent of hte disase/exposure status. |
Relative Risk | Estimates the magnitude of an association between exposure & disease & indicates the likelihood of developing the disease in the exposed relative to those unexposed. |
Repeatability | A test of measurement is repeatable & reliable if it yields identical result each time it is conducted under the same conditions. |
Representative Sample | A sample that resembles & has the same characteristics as the general population from which it is drawn. |
Residual Confounding | A spurious association due to confounding that persists even after adjustment fof the cofounder because the data on exposure to the cofounder is inaccurate due to misclassification. |
Responder Bias | A type of measurement bias that occurs when the information given by the participants is not independent of their exposure/disease status. |
Response Rate | The number of people who completed & returned a questionnaire or who participated in a interview divided by the total number of people who were eligable to participate |
Restriction | A technique used to control fpr confounding at the design stage of a study. It limilt the study to people who are similar in relation to the cofounder. |
Retrospective Study | A study in which data about the participants were collected from past records or that looks backward from disease to exposure. |
Risk | The porportion of people in apopulaiton, initially free of disease, who develope the disease within a specified time. The probability tht an event will occur. |
Risk Difference | The absolute difference in the risk of developing the disease between those exposed to a risk factor & those not exposed. |
Risk Factor | An environmental exposure, lifestyle, inborn, or inherited characteristic associated with an increase or decrease probability of occurance of a disease or other health outcome. Can be a harmful or protective occurance. |
Risk Ratio | A measure of relative risk. The ratio of the risk of becoming diseased in the exposed group to the risk of becoming diseased in the unexposed group. |
Selection Bias | Error due to systematic differences in characteristics between those who were selected for study & those who were not. |
Single Blind Trail | A trial in which either the participant or the observer who measures the outcome (but not both) is unaware of the treatment the participant is receiving. |
Standardised | A set of techiniques used to remove, as far as possible, the effects of differences in age or other onfounding variables, when comparing 2 or more populaitons. |
Standardised Mortality Ratio | The ratio of hte numbre of events observed in the study group to the number that would be expected, with appropriate allowance for age, sex & other confounders if the study population had the same (age, sex) specific rates as the standard populaiton. |
Stratification | Analysis of data in subgroups according to specified criteria such as group, socio-economic status, etc. One way of controlling for confounding effects at the analysis stage & a way of detecting effect modificatoin. |
Systematic Sample | The selection of participants for inclusion in a study using a pre-determined order |
Systematic Review | The application of strategies that limits bias in the assembly, crical appraisal & synthesis of all relevent studies on a apecific topic. They focus on peer-reviewed publications about a specific health problem. |
Trail | An epidmiological study which employs an experimental design, in which the individual are allocated to recieve or not to recieve the intervetnion under study. The assignment may or may not be done by random allocation |
Validity | The degree to which a measurement does actually measure what it purport to measure. |