Lecture 7 - Bias

Question 1

define selection bias

Answer 1

sys error in selecting participants; do participants rep pop? are participants similar in all aspects except exposure/disease?

Question 2

define information bias

Answer 2

data for outcome and exposure obtained differently; incomplete or inaccurate data collection

Question 3

What are diff terms for information bias

Answer 3

observation or measurement bias

Question 4

define confounding bias

Answer 4

results accounted for by presence of factor associating with exposure and outcome but not in causal pathway

Question 5

Selection bias affects which two observational studdies

Answer 5

CC and cohort

Question 6

What are the 4 types of selection bias

Answer 6

volunteer, non-response, exclusion, healthy worker bias

Question 7

define exclusion bias

Answer 7

exclusion criter/participant loss after randomization results in a group of people that dont rep gen pop

Question 8

Exclusion bias can also occur if

Answer 8

diff eligibility criteria for cases and controls

Question 9

what are the 4 contributing factors of healthy worker bias

Answer 9

healthy hire, healthy worker survivor effect, time since hire, beneficial effect of work

Question 10

what are the two phases of time since hire?

Answer 10

dynamic and stable phase

Question 11

what are the 6 types of info bias

Answer 11

non differential bias, differential bias, recall bias, interview bias, LTFU bias, reporting bias

Question 12

non differential and differential bias are classified as what type of info bias

Answer 12

misclassification bias

Question 13

define non differential bias

Answer 13

measurement of disease is not diff btw exposed and unexposed and vice versa

Question 14

define differential bias

Answer 14

measurement of disease is diff btw exposed and unexposed and vice versa

Question 15

in which misclassification bias does the rate of misclassification diff btw diff study groups

Answer 15

differential bias

Question 16

how do you combat recall bias

Answer 16

use controls with a disease with similar potential for search as cases, hospital records, biomarkers, blinding

Question 17

define LTFU bias

Answer 17

systematic difference in following and obtaining outcome info; problem with LTFU relates to outcome

Question 18

What are two types of reporting bias

Answer 18

social desirability bias and wish bias

Question 19

define wish bias

Answer 19

deny exposure to minimize self blame

Question 20

what is another term for LTFU

Answer 20

attrition bias

Question 21

RCTs have which bias

Answer 21

selection, performance, attrition, detection bias

Question 22

CC have which bias

Answer 22

recall and selection

Question 23

Cohort has which bias

Answer 23

selection bias due to diff rates of LTFU in exposed and unexposed

Question 24

Define random error

Answer 24

reduce precision of estimates; non-differential missclassification

Question 25

define systematic error

Answer 25

reduce validity/accuracy of estimates; differential miscclassification

Question 26

in systematic error

Answer 26

you always underestimate a parameter, therefore a predictable distance away from truth

Question 27

in random error

Answer 27

you on average get right answer but you sometimes over and underestimate

Question 28

define precision

Answer 28

replicability of value with multiple measurements

Question 29

define accuracy

Answer 29

getting results right