Podcast
Questions and Answers
What is the primary reason for requiring independent evaluation of outcomes in a study?
What is the primary reason for requiring independent evaluation of outcomes in a study?
- To avoid interviewer bias due to personal interests. (correct)
- To ensure that the treatment is effective.
- To obtain more funding for the research.
- To increase the number of participants in the study.
Which of the following is the least biased source of exposure information?
Which of the following is the least biased source of exposure information?
- Self-reported data from subjects.
- Surveys conducted by interviewers.
- Focus group discussions.
- Pre-existing records. (correct)
What type of bias occurs when a study subject alters their responses based on their treatment knowledge?
What type of bias occurs when a study subject alters their responses based on their treatment knowledge?
- Selection bias.
- Information bias.
- Prevarication bias. (correct)
- Confirmation bias.
Which strategy can diminish loss to follow-up in study design?
Which strategy can diminish loss to follow-up in study design?
In a cohort study, what type of bias is primarily associated with the information collection process?
In a cohort study, what type of bias is primarily associated with the information collection process?
What is a key aspect of bias that distinguishes it from chance or confounders?
What is a key aspect of bias that distinguishes it from chance or confounders?
What type of bias is specifically related to the selection criteria of participants in a study?
What type of bias is specifically related to the selection criteria of participants in a study?
Which of the following best describes attrition bias?
Which of the following best describes attrition bias?
Why is selection bias a significant concern in retrospective cohort studies?
Why is selection bias a significant concern in retrospective cohort studies?
Which of the following is an example of survivorship bias?
Which of the following is an example of survivorship bias?
What is a common issue related to nonresponse bias?
What is a common issue related to nonresponse bias?
What is self-selection bias also known as?
What is self-selection bias also known as?
What type of selection bias occurs when some members of the population are less likely to be included than others?
What type of selection bias occurs when some members of the population are less likely to be included than others?
In which study design is selection bias most likely to occur?
In which study design is selection bias most likely to occur?
What characterizes a confounding factor?
What characterizes a confounding factor?
Which of the following is NOT a potential effect of confounding factors?
Which of the following is NOT a potential effect of confounding factors?
What strategy can be used to determine if a variable is a confounder?
What strategy can be used to determine if a variable is a confounder?
In epidemiological studies, what does bias represent?
In epidemiological studies, what does bias represent?
When evaluating confounders, which factor is considered unreliable?
When evaluating confounders, which factor is considered unreliable?
What is the primary purpose of identifying confounding factors in research?
What is the primary purpose of identifying confounding factors in research?
Which of the following best describes a characteristic of chance?
Which of the following best describes a characteristic of chance?
Which of these statements about confounders is true?
Which of these statements about confounders is true?
What is the primary issue caused by recall bias in case control and retrospective cohort studies?
What is the primary issue caused by recall bias in case control and retrospective cohort studies?
Which of the following sources of information biases involves differences due to the researcher’s influence?
Which of the following sources of information biases involves differences due to the researcher’s influence?
What consequence can arise when diseased individuals think more deeply about the causes of their disease?
What consequence can arise when diseased individuals think more deeply about the causes of their disease?
Which type of information bias involves participants providing untruthful responses during studies?
Which type of information bias involves participants providing untruthful responses during studies?
Which factor can significantly affect the recruitment of participants in health-related studies?
Which factor can significantly affect the recruitment of participants in health-related studies?
What defines the phenomenon of observer bias in research studies?
What defines the phenomenon of observer bias in research studies?
Why are healthy populations more frequently selected as subjects in studies compared to sick individuals?
Why are healthy populations more frequently selected as subjects in studies compared to sick individuals?
In which scenario is interviewer bias most likely to occur?
In which scenario is interviewer bias most likely to occur?
What effect does information bias generally have on study findings?
What effect does information bias generally have on study findings?
Flashcards
Confounder
Confounder
A third factor that is associated with both the exposure and the outcome, and can influence the observed association between them.
Chance
Chance
The possibility of something happening, often expressed as a probability.
Bias
Bias
A systematic error in an epidemiological study that leads to an incorrect estimation of the association between exposure and outcome.
True Association
True Association
Signup and view all the flashcards
Apparent Association
Apparent Association
Signup and view all the flashcards
Independent Risk Factor
Independent Risk Factor
Signup and view all the flashcards
Confounder Evaluation
Confounder Evaluation
Signup and view all the flashcards
Controlling for Confounders
Controlling for Confounders
Signup and view all the flashcards
Selection Bias
Selection Bias
Signup and view all the flashcards
Self-Selection Bias
Self-Selection Bias
Signup and view all the flashcards
Attrition Bias
Attrition Bias
Signup and view all the flashcards
Sampling Bias
Sampling Bias
Signup and view all the flashcards
Survivorship Bias
Survivorship Bias
Signup and view all the flashcards
Nonresponse Bias
Nonresponse Bias
Signup and view all the flashcards
Selection Bias
Selection Bias
Signup and view all the flashcards
Observational Bias
Observational Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Interviewer Bias
Interviewer Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Recall Bias
Recall Bias
Signup and view all the flashcards
Prevarication Bias
Prevarication Bias
Signup and view all the flashcards
Selection Bias in Case-Control Studies
Selection Bias in Case-Control Studies
Signup and view all the flashcards
Selection Bias in Cohort Studies
Selection Bias in Cohort Studies
Signup and view all the flashcards
Information Bias
Information Bias
Signup and view all the flashcards
Study Notes
Confounder & Bias
- A confounder is a third factor associated with an exposure and an outcome, but independent of the exposure-outcome relationship.
- It's a risk factor for the outcome.
- Confounders can simulate, hide, or alter the strength of an association between a risk factor and an outcome.
- This can lead to over or underestimation of the true association, or even change the direction of the observed effect.
Characteristics of a Confounder
- Associated with the exposure.
- Associated with the outcome.
- Independent of the exposure-outcome relationship
Example of Confounding Factor
- Exposure 1 (e.g., ethnicity) may appear to be associated with an outcome (e.g., pneumonia).
- However, a confounding factor (e.g., crowding) could affect both the exposure and the outcome.
Example of Confounding Factor (1)
- Apparent association: ethnicity and pneumonia.
- Confounding factor: crowding.
Independent, Dependent, Confounding Variables
- Independent variable: Coffee drinking.
- Dependent variable: Heart disease.
- Confounding variable: Cigarette smoking.
Example of Confounding Factor (Diagram)
- Smoking as confounder.
- Alcohol use as exposure.
- Lung cancer as outcome.
Determining if a Factor is a Confounder
- Find the crude overall estimate of association between exposure and outcome.
- Find the adjusted estimate after controlling for the factor.
- If the two estimates are different, the factor is a confounder.
Selection of a Potential Confounder
- Depends on knowledge of the disease, previous evaluation of the variable, and investigator judgment.
- Statistical significance isn't sufficient to determine confounders.
Evaluating the Role of a Confounder
- Decide on its presence or absence.
- Determine the magnitude of its effect.
- Determine its direction
Bias
- Bias is a systematic error in an epidemiological study.
- It leads to an incorrect estimation of the association between exposure and outcome.
- Bias represents a deviation from the truth, causing distorted results and wrong conclusions.
Bias (Characteristics)
- Unlike chance, or a confounder, bias cannot be measured quantitatively.
- Bias is almost impossible to be dealt with during analysis.
- Bias must be considered during the study design stage.
Sources of Bias
- The method of selecting study participants.
- The ways information is obtained, reported, or interpreted.
Types: Selection Bias
-
Participants’ inclusion depends on an association with other axes (e.g., in a cohort study: exposure; in case-control: disease/outcome).
-
There are various types of selection bias such as:
- Sampling bias: When some members of a population are less likely to be included than others.
- Attrition bias: Participants leaving the study.
- Self-selection bias (volunteer bias): Participants decide their own participation.
- Survivorship bias: Focus solely on successful individuals.
Types: Selection Bias (Specific examples)
- In cohort study : If selection of exposed and non-exposed related to development of the outcome.
- In case control: selection of the cases and control depends on different criteria that are related to exposure status.
Selection Bias (General)
- A problem in both case-control and retrospective cohort studies.
- Exposure and disease occurred before the study.
Information Bias
- Results from a systematic difference in how information, about exposure or outcome, is obtained from study groups.
Sources of Information Bias
- Recall bias: Individuals with the disease may recall exposure differently than controls.
- Investigator bias: The investigator's bias may influence data collection.
- Data quality: Problems with data collection.
- Prevarication: Participants intentionally provide inaccurate responses
Types: Recall Bias
- Individuals with certain diseases may report or remember previous exposures differently from those without the disease.
- Individuals exposed to a certain factor may report subsequent events differently from those not exposed.
- This can lead to over or under estimation of the true association. Example: birth defects.
Types: Investigator Bias
- Systematic collection of information may support expected conclusions (unconsciously or consciously).
Types: Interviewer Bias
- Systematic differences in recording or interpreting information from study participants.
- Can occur in all types of studies.
Types: Interviewer Bias (Case-Control studies)
- Differential probing of participants’ exposure history in case-control studies.
Sources of Exposure and Outcome Information
- Use pre-existing records.
- Multiple data sources.
- Uniform criteria for data collection.
- Practical methods to decrease loss to follow-up.
Prevarication
- Participants over or under-estimate their outcome due to knowledge of their treatment, to please the interviewer, or seeking secondary gain.
Level of Operation of Biases
- A visual representation demonstrating where each type of bias can occur, in different study design settings.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
