Biostats Flashcards
_______ bias is the bias that is associated with researchers choosing who is included in the study. This can lead to no external or internal validity
Selection
To increase external validity, you will want to do what in selecting your participants?
Get a sample population that is representative of the target population; where they live, age, race, socioeconomics
______ bias is a type of selection bias in which some inidividuals in a community may not be selected: selecting via addresses; some people do not have a permanent address
Sampling
_______ bias can be corrected with incentives for filling out surveys
non response bias
The _______ _______ occurs when a study recruits the exposed group from a general occupational cohort and then the unexposed group from the general population
healthy worker effect: most of the workers are healthy and able to go to work
Smoking group (occupational) will be of good health where the people who are not working could have various health levels
_______ bias is when individuals in two groups are associated with the characteristic of the exposure
Two groups are chosen from the hospital with and without lung cancer and compare how many people smoke in each group in hopes of finding how much smoking can cause lung cancer….but smoking could cause other disease too in the group of controls (Heart disease, diabetes, etc) and some of those patients could be admitted to the hospital because of those diseases that are also associated iwth a higher risk from smoking
Berkson’s bias…. can overcome by having a control group with an outcome (say a broken bone) that does not correlate with the exposure (smoking)
_______ can skew the results by underestimating the results of the exposure on the overall outcome
Loss to follow up: you now have less people who have positive disease at the end bc they may have died, moved, got bored, etc
_______ bias is common in case control studies and can lead to an over or underestimation of the exposure because there is a difference in the accuracy and completeness of the data
Recall bias
Individuals with skin cancer might be more likely to report tanning bed use and may over estimate whereas people without skin cancer may under-report because the visits can blur and become forgotten…. what bias is this?
Recall bias
how can you decrease recall bias?
Written records
Study exposures in recent pass
_______ bias is when researchers use inadequate methods to collect data: imprecise, self reported, etc
Measurement bias
Hoe can you avoid measurement bias?
Carefully research procedures
Regular calibration
________ _______ is when people change their behavior because they know that they are being studied; increased adherence, etc
Hawthorne effect
How can you avoid the Hawthorne effect?
secrete observation
_______ bias is when groups are treated differently;
Cavities in people who floss and who do not; dentists might do a more thorough exam on people who do not floss because they will expect cavities
Procedure bias
_______ _______ bias occurs when the people conducting the experiment expect an outcome and therefore round up, etc
Observer expectancy bias
How can you overcome an observer expectancy bias?
Double blinding
_______ bias can occur when there is an independent factor that is associated with the exposure and the outcome
Confounding
Obesity and colorectal cancer—- red meat and processed meat; obese poeple may consume more
How can you eliminate confounders?
Multiple repeated studies
Crossover studies: participants are their own controls
Randomization
Matching participants
_______ _______ are when participates are stratified with a specific factor of an outcome
Obesity and colorectal cancer in MALES OR FEMALES; the sex becomes the ______ _______
Effect modifier
_______ ________ bias occurs when the disease is diagnosed early and seems to survive longer (just because they were diagnosed early)
Lead time bias
Early detection can be confused with increased survival
How can you overcome lead time bias?
Back end survival
______ ______ bias where slowly progressive diseases are more prone to be detected compared to aggressive diseases
Length time bias
