Term
| ___ epidemiological studies have controlled assignment. ____ studies have uncontrolled assignment. This being said, which study is considered active and which is passive? |
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Definition
| experimental (active), observational (passive) |
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Term
| What is the main difference between experimental and observational studies? |
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Definition
| experimental, the experimenter has direct control over who gets what condition. the difference is NOT random assignment. |
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Term
| the ____ group in an experiment receives no treatment, whereas the ___ groups recieve different treatments from each other (drug a and drug b) |
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Definition
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Term
| example of an observational study |
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Definition
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Term
| 3 types of study designs on the test |
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Definition
| prospective, unmatched case-control, and matched case-control |
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Term
| what study design will involve absolute risk/incidence rate in every calculation? |
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Definition
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Term
| which of bradford hill's criteria is most important? |
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Definition
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Term
| can you calculate relative odds? |
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Definition
| yes, but it's not done because we do relative risk instead because it uses incidence and prevalence |
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Term
| difference between coherence and biological plausibility |
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Definition
| coherence is logical, biological plausibility is well grounded in science |
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Term
| how are effects measured in an experimental study? |
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Definition
| comparing the experimental and comparison or control groups |
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Term
| how do you avoid bias in an experimental study? |
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Definition
| members of the experimental and control groups should be similar in as many ways as possible |
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Term
| a ___ is an experiment in which the unit of allocation to receive a preventative intervention regimen is an entire community or political subdivision. |
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Definition
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Term
| the administration of a test regimen to humans to evaluate its safety and efficacy. usually refers to a rigorously designed and executed experiment involving test and control treatments and randomization. |
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Definition
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Term
| 3 main types of clinical trials |
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Definition
| prevention trial, intervention trial (secondary prevention), and therapeutic trial (tertiary prevention) |
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Term
| in a ____ clinical trial, the agent or procedure is given to relieve symptoms or improve survivorship in diseased individuals. |
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Definition
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Term
| ___ clinical trials could be designed to reduce/eliminate long-term impairment and disability, minimize suffering, or promote adjustments to irremediable conditions |
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Definition
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Term
| in ___ clinical trials, the researcher intervenes with a disease for people at increased risk (obese people and heart disease). classic example? |
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Definition
| intervention - MRFIT (multiple risk factor intervention trial) |
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Term
| in ___ clinical trials, the effectiveness of a prevention procedure (exercise to prevent heart disease) are determined. These generally involve health eating habits, physical fitness, and quality of life. |
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Definition
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Term
| in ___ studies, nature is allowed to take its course |
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Definition
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Term
| in ___ studies, changes or differences in one characteristic are studied in relation to changes or differences in others, without the intervening of the investigator. |
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Definition
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Term
| 2 other names for observational studies |
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Definition
| non-experimental or quasi-experimental |
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Term
| 4 types of observational studies |
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Definition
| case-control, cross-sectional, historical prospective, prospective (logitudinal) |
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Term
| ___ studies can be considered a "slice in time" because they involve POINT PREVALENCE. |
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Definition
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Term
| in ___ studies, we begin with a DISEASED person and look back to see waht caused it. |
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Definition
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Term
| in ___ studies, we begin with EXPOSED people and look FORWARD to see how it's affected them. |
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Definition
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Term
| survey studies are usually ___ studies |
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Definition
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Term
| cross sectional studies are AKA |
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Definition
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Term
| in a cross-sectional study, can the temporal sequence of cause and effect be determined? |
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Definition
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Term
| a group of women are interviewed to determined their use of video display terminals and whether they had a miscarriage. this is a ___ study (observational) |
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Definition
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Term
| 3 advantages to cross sectional studies |
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Definition
| inexpensive and simple to do, no subjects are exposed to the causal agent, can be the baselline for future prospective studies |
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Term
| 5 limitations to cross sectional studies |
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Definition
| establishes association but not causation, impossible to ensure that variables are equally distributed among groups, often depends upon recall of the patients, Neyman Bias, may have an uneven sample size |
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Term
| the ___ bias happens when early deaths and those in which evidence of exposure has disappeared are missed. |
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Definition
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Term
| case control studies begin in the ___ and look toward the ____ |
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Definition
| begin in the present and look toward the past |
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Term
| a ____ study involves diseased and non-diseased poeple, NOT exposed and unexposed |
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Definition
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Term
| 5 advantages of a case-control study |
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Definition
| can be done quickly, usually cheap, smaller number of subjects, no attrition problems, minimal ethical issues |
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Term
| 2 disadvantages to case-control studies |
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Definition
| difficult to determine causation, cannot determine incidence |
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Term
| 5 times when you use a prospective study |
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Definition
| when you can associate the disease with a specific exposure, when the exposure is rare but the incidence of the disease among the exposed is high, when the time between the exposure and the disease is short, when appropriate funds are available, and when the investigated has a long life expectancy |
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Term
| 2 types of prospective studies |
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Definition
| people initially identified with know diseases and a cohort of unknown diseases are followed forward in time :: a cohort where diseased status is initially unknown is followed in time |
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Term
| a prospective study involves what 3 calculations? |
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Definition
| incidence, prevalence, and relative risk |
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Term
| in a ___ study, the investigator usually selects their sample from a defined population, which consists of exposed and unexposed people. |
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Definition
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Term
| in a ___ study, the sample is followed over time and data is collected at a minimum of 2 points (beginning and end) to compute incidence rates between selected exposures and outcomes |
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Definition
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Term
| 6 advantages to doing a prospective study |
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Definition
| management of confounding varaibles through random selection, study is not limited by past constraints, allows directionality (a precedes b), helps assess causation, no recall necessary, calcualtion of incidence and prevalence |
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Term
| 3 disadvantages of a prospective study |
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Definition
| expensive and time consuming, ethical problems, attrition problems |
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Term
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Definition
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Term
| a ____ study is a cohort study that is done by reconstructing data about subjects at a given time in the past. |
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Definition
| historical prospective study |
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Term
| a ___ study uses pre-existing records to evaluate the health of a population, in terms of a particular disease of interest at the present time. |
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Definition
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Term
| a study of people exposed to the atomic bomb in Hiroshima is an example of what kind of study/ |
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Definition
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Term
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Definition
| trying to find results that the public wants to hear |
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Term
| a ____ study is the only direct measure of risk |
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Definition
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Term
| which is a more accurate estimation of risk? Relative risk or Odds ratio? |
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Definition
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Term
| which is a better measure of risk? Prospective (direct) or case-control (indirect)? |
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Definition
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Term
| the proportion of a disease attributable to a particular exposure |
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Definition
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Term
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Definition
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Term
| the proportion of the absolute risk in the exposed group that is attribuatble to the exposure |
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Definition
| proportion of attributable risk |
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Term
| What does the proportion of attributable risk tell us? |
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Definition
| if PAR = 12% for smoking and cancer, then there should be a total reduction of 12% in the incidence of cancer in this population if smoking were eliminated |
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Term
| what calculation answers these questions: is there an association between exposure and disease? if so, how strong is that association? |
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Definition
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Term
| what does a relative risk factor <1 tell us? =1? >1? |
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Definition
| <1 - protective factor (negative association - you SHOULD engage in this behavior because it is beneficial to your health :: =1 - null hypothesis, equal risk :: >1 - risk (positive association) - you SHOULD NOT engage in this behavior because it is harmful to your health. |
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Term
| what does a relative risk of 1.61 mean? |
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Definition
| there is a 61% increase of risk over the null hypothesis. |
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Term
| when is Odds Ratio a good approximation of relative risk? |
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Definition
| the cases studied are representative of all people with the disease in the population from which the cases were drawn with regard to the history of exposure :: when the controls studied are representative of all people without the disease in the population from which the cases were drawn wtih regard to the history of exposure :: when the disease being studied is infreqeunt |
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Term
| what studies use odds ratios? |
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Definition
| case-control, historical prospective, cross-sectional |
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Term
| 2 types of causal judgement |
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Definition
| overall and one study at a time |
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Term
| 3 epidemiological processes used to aid in determining causation |
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Definition
| clinical observations, analysis of data, multiple studies with different designs and investigators |
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Term
| a ___ is a variable that can cause or prevent the desired outcome |
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Definition
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Term
| ____ literally means "to mix together" |
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Definition
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Term
| ___ can occur when adjustment is made for any factor that is caused in part by the exposure and also is correlated with the outcome |
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Definition
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Term
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Definition
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Term
| ___ error is the portion of variation in a measurement due to chance (no association with any other known variables) |
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Definition
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Term
| ____ error is the portion of variation in a measurement that originates from a recognizable source (ex: math errors) |
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Definition
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Term
| systematic error are due to sloppiness and could also be called type ___ errors |
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Definition
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Term
| what 3 conditions must be ruled out for a study to be considered valid |
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Definition
| chance, bias, and confounders |
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Term
| 9 Bradford Hills Criteria |
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Definition
| strength of association, dose-response relationship (biological gradient), temporal relationship, specificity of association, consistency of association, biological plausibility, coherence, alternative explanations ruled out, analogy |
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Term
| which BH criteria? is there a credible biological mechanism to explain the development of the disease or increased risk for the disease? |
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Definition
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Term
| which BH criteria? do the findings about the relationship between the exposure and the disease agree with known facts or existing knowledge/ |
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Definition
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Term
| which BH criteria? to what extent has the possibility of alternative explanations been adequately considered and excluded? |
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Definition
| alternative explanations ruled out |
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Term
| which BH criteria? when action is taken, does the disease still occur? |
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Definition
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Term
| which BH criteria? examine the relative risks, odss ratios, and confidence intervals |
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Definition
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Term
| which BH criteria? as dose of exposure increases, does risk of disease increase? |
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Definition
| dose-response relationship |
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Term
| which BH criteria? dose exposure precede disease? |
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Definition
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Term
| which BH criteria? is the exposure specific to the disease? |
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Definition
| specificity of association |
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Term
| which BH criteria? is there consistency in the findings reported in different studies, using different study designs, methods, or in different populations? |
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Definition
| consistency of association |
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Term
| by examining a single study at a time according to BH criteria, the reviewer ultimately comes up with 2 stacks of studies: |
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Definition
| those that support causality and those that dont |
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Term
| An RR and OR between __ and __ suggests a causal relationship |
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Definition
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Term
| and OR or RR greater than __ means that an idea MIGHT be causal and further investigation should be done |
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Definition
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Term
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Definition
| 31 of 35 studies suggest a causal relationship - consistency = 89% (31/35) |
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Term
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Definition
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Term
| specificity of association |
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Definition
| the idea that one cause should lead to one outcome, although this is not always true as with obesity and heart disease/stroke |
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Term
| steps in an unmatched case-control study |
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Definition
| select cases and controls, determine past exposure -- MUST be done in this order |
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Term
| in a matched case-control study, the controls are selected by matching each to a case based on ?? |
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Definition
| variables that are known to be related to disease risk |
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Term
| which study design is stronger? Matched or unmatched case-control |
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Definition
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Term
| 4 types of Matched case-control studies |
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Definition
| Concordant pairs: pairs in which both the cases and controls were exposed, pairs in which both the cases and controls were unexposed :: Discordant pairs: Pairs in which the case was exposed and the control was not, Pairs in which the control was exposed and the case was not |
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Term
| Are concordant or discordant pairs more important in matched case-control studies? |
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Definition
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Term
| Odds ratio in a matched case-control study is based on ____ pairs only. |
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Definition
| discordant (b and c) -- a and d are ignored |
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Term
| RR is calculated directly in a ____ study. Because it can't be calculated directly in a ____ study, OR is calculated instaed. |
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Definition
| prospective, case-control |
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Term
| BH's ______: If more exposure leads to more disease, then the case for causality is strengthened. |
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Definition
| dose-response relationship |
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Term
| implication of BH's biological plausibility and specificity. |
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Definition
| plausibility and specificity strengthen the case for causality if it is proven, however lack of these do not weaken it ... for instance John Snow and Cholera (at the time, his hypothesis was not biologically plausible) |
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Term
| BH's criterion, _____ has to do wtih whether the phenomena makes logical sense, although it does not have to correspond with current theories, it should not conflict with them. |
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Definition
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Term
| ___ is the weakest form of evidence in BH's criteria |
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Definition
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Term
| BH's criterion, ______ is when anything well-known is used to explain something unknown |
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Definition
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Term
| 3 cognitive methods of causality |
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Definition
| biological plausibility, coherence, analogy |
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Term
| Implications of BH's criteria |
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Definition
| they do not all need to be met to establish causality, but the more the better |
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