Unit 2

Question 1

Bias definition

Answer 1

systematic error in design, conduct, or analysis of a study that results in a mistaken of an exposure’s effect.

differs from random error becuase it is systematic

Question 2

selection bias, name the 3 forms

Answer 2

systamatic error in slecting one or more of the study groups compared

affects internal validity of the study

3 forms: non response, loss to follow up, health worker effect

approaches to adress: caeful study design, use of includion and exculsion criteria, and reduce non response

Question 3

Selection bias: non-response

Answer 3

a differenc ien chactersitic of participant vs. non-participants, if differen it large will have an effect on outcome

Question 4

Slection bias: loss to follow up

Answer 4

paricipants who withdraw from a study are systematically different from those who remain

Question 5

Selection bias:health worker effect

Answer 5

able to participate are often in greater health than thoes who cannot ie. diffrence in symptoms

Question 6

Information bias

Answer 6

systamatic error occurs when the means for obtaining information about the subjects in the study are inadequate, as a result the information gathered regarding exposures and or disease outcome are incorrect

Question 7

Information bias: miss-classification bias

Answer 7

misclassify subjects, classify as exposed when not and vice versa

two types: differenital and non differential

approaches: use best available data collection tools, reduce misinformation reported ie. shotren recall period

Question 8

Infomraiton bias: miss-classification bias: differential missclassification

Answer 8

one group is more likely to be inaccurately assinged between two groups

ex. a women with a baby with malfomration tended to remember infection that occured during htie rpreganices then did mother with normal infants

will tent to lead to a assocaiton found

Question 9

Infomraiton bias: miss-classification bias: non-differential missclassification

Answer 9

inaccuracy in the information obtained form any study group, all groups are equally as likely to be accurate or inaccurate, problems with data collection

well tend to lead to a bias toward null

Question 10

Informaiton bias: recall bias

Answer 10

occurs when certain groups are more likely to remember certain info than another group

Question 11

Informaiton bias: reporting bias

Answer 11

occurs when paticular informaition because of attributed beilies and perceptions

Question 12

confouding

Answer 12

incorrectly conclude that a causual assocation between two factors exists, assoication is disorted by another facotr that was not considered

Question 13

Way to address confoudning

Answer 13

matching between cases and controls, data analysis 1. stratify, 2. adjustment, randomization, restriction or exclusion (exclude based on presence of a given factor)

Question 14

Causation

Answer 14

each component of a disease is necessary for disease but NOT sufficient to cause the disease on its own, however all factors come together to form a sufficient cause

Question 15

Direct vs. indirect causation

Answer 15

direct: indicated that a factor directly causes a disease or health outcome without any step in between
indirect: indicated that a factor causes disease but not before going through intermediate steps