Definitions Flashcards
What is epidemiology?
Study of distributions and determinants of health related events in a population to control disease and illness and to promote health.
What is descriptive epidemiology?
Who, what and when
What are determinants?
analytical epidemiology (why and how)
Name the 6 core functions?
Surveillance, Field investigation, analytical studies, evaluation, linkages and policy development
What is surveillance?
Portray disease patterns that are ongoing so control and prevention measures can be developed or applied.
What is field investigation?
Determine sources of disease to learn about natural history, descriptive epidemiology (first 3 W’s) and risk factors of disease
*** Before determining appropriate interventions
What is analytic studies?
Advance the information generated by descriptive epi techniques
** it is taking information and generating an “action plan” to prevent cure or help disease
What is evaluation?
To evaluate how effective, efficient and relevant the “action plan” is.
What are linkages?
Communicate with other public health and healthcare professionals
What is policy development?
Give ideas and thoughts to prevent and control disease and illness. To promote health.
Distribution refers to –> ?
Who
Determinants refers to –>?
Risk factors
What are case definitions?
Criteria used to define a disease/condition for public health surveillance
What is confounding?
A 3rd variable that distorts an association between the exposure and the outcome.
What is the definition of controlling for the confounding?
Purpose of controlling: to get a more precise accurate, truer-estimate of the measure of associated between exposure and outcome.
Study Design Stage:
Randomization, restriction and matching
Analysis of Data stage
Stratification, multivariate statistical analysis
In terms of controlling for confounding what is randomization and what is a strength and weakness of it?
Randomization technique hopefully allocates an equal number of subject with the known confounders into each intervention group
S: Stratified version more precisely assures equal-ness
Serves its purpose with appropriate size
W: Practical only for interventional studies
Doesnt guarantee successful, equal allocation
Sample size may not be large enough to control for all unknown confounders
In terms of controlling for confounding what is restriction and what is a strength and weakness of it?
Study participation is restricted to only subjects who do not fall within pre-specified category of the confounder
S: Does not negatively impact internal validity
Convenient, inexpensive and straight forward
W: Can negatively impact external validity
In terms of controlling for confounding what is matching and what is a strength and weakness of it?
Study subjects selected in matched pairs related to the confounding variable to equally distribute confounder among each study group
S: Intuitive
W: Difficult to accomplish, time consuming and expensive. Does not control for any confounders other than those matched on
In terms of controlling for confounding what is stratification and what is a strength and weakness of it?
Descriptive and statistical analysis of data evaluating associated between exposure and outcome within the various strata.
S: Intuitive, Straight forward
W: Impractical for simultaneous control of multiple confounders
In terms of controlling for confounding what is multivariate analysis and what is a strength and weakness of it?
Statistical analysis of data by mathematically factoring out the effects of the confounding variables.
S:Can control multiple confounders
W: Can be time consuming, requires people who can interpret data correctly.
What is the definition of bias?
Non-random error in study design or conduct leading to erroneous results.
Distorts the relationship between exposure and outcome.
What are the 3 elements of bias impact?
Source/Type
Magnitude/Strength
Direction
What is selection-related bias?
Any aspect in the way the researcher selects or acquires study subjects which creates a systematic difference between groups.
What is measurement-related bias?
Any aspect in the way the researcher collects information or measures/observes subject which creates a systematic difference between groups
What is selection bias? Give examples
The way study subjects are selected generates differences in groups (#1 bias we worry about)
EX: Healthy worker bias, self-selection/participant (responder) bias
What is recall?
Recall: A differential level of accuracy/detail in provided information between study groups.
What is Hawthorne effect?
Hawthorne: individuals alter/modify their behavior because they are part of a study and know they are under observation
What is contamination bias?
Members of the control group accidentally or outside of the study protocol receive the treatment or are exposed to the intervention being studied
What is compliance/adherence bias?
Groups being interventionally studied have different compliance/adherence with study protocol/treatments.
What is lost to follow up bias?
Groups being studied have different withdrawal or lost to follow up rates or there are other differences between those that stay in the study and those that withdraw or are lost to follow up
What is the interviewer bias? Give example
A systematic difference in soliciting, recording or interpreting on the part of the researcher.
EX: when interviewer knows what group patient is in and treats the interview different
What is diagnosis/surveillance (expectation) bias?
Different evaluation, classification, diagnosis or observation between study groups.
*** This is the Hawthorne effect for researches, they act differently depending on what they think they should find in results.
What is lead time bias?
AN apparent benefit from a healthcare screening due to the early detection of disease despite an unchanged clinical outcome.
***Does not help you live longer, just helps you know you have disease longer
What are 4 ways for controlling for biases?
- Blinding/Masking
- Use multiple sources to gather all information
- Randomly train observers/interviewers for data collection
- Build in as many methods necessary to minimize loss to follow up
