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Epi L06
| Question | Answer |
|---|---|
| _____ studies are either observational or experimental | epidemiological studies are either |
| _____ studies are considered "natural" experiments while experimental studies are considered true experiments | observational |
| _____ studies most closely resemble conrolled laboratory experimenta nd serve as models for the conduct of observational studies | experimental |
| what are the gold standard of epidemiological research (high status and validity, can pick up small and modest effects)? | experimental studies |
| what are the 2 components to equipoise? | 1. sufficient belief to justify exposing some subjects to new treatment, 2. sufficient doubt to justify withholding new treatment from some subjects |
| which term describes the out come of these questions: is doing the trial ethical? is NOT doing a trial ethical? | equipoise |
| _____ studies are either observational or experimental | epidemiological studies are either |
| _____ studies are considered "natural" experiments while experimental studies are considered true experiments | observational |
| _____ studies most closely resemble conrolled laboratory experimenta nd serve as models for the conduct of observational studies | experimental |
| what are the gold standard of epidemiological research (high status and validity, can pick up small and modest effects)? | experimental studies |
| what are the 2 components to equipoise? | 1. sufficient belief to justify exposing some subjects to new treatment, 2. sufficient doubt to justify withholding new treatment from some subjects |
| which term describes the out come of these questions: is doing the trial ethical? is NOT doing a trial ethical? | equipoise |
| treatment allocated to ______: do quality of life improve more with individuals receiving an implant supported prosthesis or conventional denture? | individual RCT |
| treatment allocated to _____: does fluoride in the water supply decrease the frequency of dental caries in a community compared to a similar community witout such water treatment? | entire communities RCT |
| what is the goal of preventive RCTs? | keep healthy people well |
| what is the goal of therapeutic RCTs? | treat (or cure) disease |
| what is a reference population in an RCT? | general group to whom results of the trial should be applicable (all humans, or some restrictions) |
| what is the study/experimental population in an RCT? | people who are considered for enrollment in a trial, potential participants |
| what are the 4 elements in informed consent? | 1. teratments, 2. potential outcomes, 3. randomization, 4. what is required of them |
| when do you obtain informed consent? | prior to randomization |
| what does randomization mean? | each individual has the same chance of receiving each possible treatment |
| name 4 benefits/strengths of randomization | 1. unbiased assignment to treatment groups, 2. known and unknown confounders are balanced - "on average", 3. leads to comparability, 4. minimizes selection bias and confounding |
| name some methods of randomization | 1. coin toss, 2. table of random numbers, 3. computer-generated random numbers |
| name 3 groups the active treatment group can be randomized into? | 1. new treatment, 2. other doses of same treatment, 3. otehr: combination therapy (usual care + new treatment) |
| name 2 groups the comparison group can be randomized into? | 1. placebo: inert agent that looks indistinguishable from active agent, 2. other: usual care - current treatment in use |
| what is the purpose of placebo? | minimizing bias |
| name 4 uses of placebo: | 1. makes groups are comparable as possible, 2. depends on subjectivity of outcome, 3. can't be done in some situations (pills vs surgery), 4. allows study to be "blinded" |
| what is single-blind? | subjects unaware of treatment group |
| what is double-blind? | both subjects and investigators unaware of treatment groups (can't be done in some situations) |
| what is triple blind? | the subjects, investigators, and investigators evaluating the outcomes are all unaware |
| does non compliance make the compared groups more alike or unalike? | more alike |
| how can you enhance compliance to a design? | pick an interested group and design a simple protocol, frequent contact with subjects, incentives to continue, |
| what is non-compliance? | failure to adhere to the study protocol |
| how can you assess compliance? | 1. ask subjects if they adhered, 2. pill counts, 3. biological measures (blood, urine) |
| T/F: you want the groups to be as alike as possible, except the variable being tested | true |
| what is the "gold standard" of epidemiologic research? | random control trials |
| what are 3 practical issues you may encounter with randomized controled studies? | 1. costs, 2. follow-up, 3. compliance |
| what is an ethical issue you may encounter with randomized controlled studies? | equipoise |
| which 2 factors can be minimized in randomized controlled trials? | bias and confounding |
| if subjects are grouped by disease, what study type is it? | case-control |
| if subjects are grouped by exposure, what study type is it? | retrospective cohort |
| which type of measure of disease frequency best describes the percentage of post-graduate dental students who had colds the day of final examination? | prevalence |
| what is the prevalence on July 1st? 1,000 people to start, 30 people developed measles on June 30, 20 people develop measles on Sept 30, 8 people are lost to follow-up on march 31, 24 ppl lost on nov 30 | 30/992 |
| what is the cumulative incidence of mealses for this study? 1,000 people to start, 30 pp develop measles on June 30, 20 pp develop measles on Sept 30, 8 people are lost to follow-up on march 31, 24 ppl lost on nov 30? | 50/1000 |
| T/F: you only subtract the people who have the disease at the beginning of the study | true |
| successful treatment programs that would shorten the duration of a disease primarily affects: incidence or prevalence | prevalence |
| which are usually not included in examples of descriptive epidemiologic studies: a. cohort studies, b. counts, c. case series, d. cross-sectional studies | a. cohort studies |
| T/F: cohort studeis enable the investigator to study cause and effect because of temporality of exposure and disease is known | true |
| what is the number of new cases of disease in a group of people at risk of disease divided by the total disease-free observation time for the group? | incidence rate |
| whit is the proportion of a population that has specified disease at a given point in time? | prevalence |
| which type of measure of disease frequency best describes the percentage of men found to have elevated blood pressure at their initial evaluation in a health center? | prevalence |
| which type of disease frequency: % of students enrolled in a college who developed influenza | cumulative incidence |
| the proportion of new cases of disease in a population at risk during a defined interval or time | cumulative incidence |
| which measure of disease frequency best describes the percentage of students enrolled in a course who had sore throats on the first day of school | prevalence |
| which technique used in experimental studies can be directly applied in cohort studies? | randomization |
| T/F: total population contributes to the denominator of cumulative incidence | false |
| T/F: a case-control study is the most efficient design for studying the health effect of rare exposures? | false: cohort |
| T/F: a retrospective cohort study is more efficient than a prospective cohort study for studying disease with long latent and induction period | true |
| T/F: a major advantage of randomized clinical trials is that it rules out self-selection of patients to the different treatment groups | true |
| T/F: loss to follow up can be a problem in observational studies but not experimental ones | false: problem in both |
| an important advantage of placebo controlled experimental study is that is permits masking of study subjects and study investigators | true |
| which two study designs provide the best evidence to support Hil's causal guideline on temporality? Be as specific as possible | prospective cohort and randomized clinical trials (when exposure comes before the outcome) |
| In 2000, the number of new cases if flu was 50 in Somerville and 1,075 in Boston. which city had a higher cumulative incidence of influenza? | can't be determined |
| a study that compares prevalence of high blood pressure is which type of study? | cross-sectional (because it's a prevalence study) |
| a process whereby the investigator assigns subjects to either the treatment or comparison group is known as what: non-compliance, equipoise, randomization, blinding | randomization |
| T/F: when calculating incidence rate of a disease, it is necessary to follow all subjects for the same length of time | false: |
Created by:
jksuite