Bias- Block 1

Question 1

what are the 4 major types of information biases in cohort studies

Answer 1

recall
observer
detection
latency and accumulation

Question 2

what are the 4 major types of selection biases in cohort studies

Answer 2

volunteer/non-response
referral
drop out
healthy worker effect

Question 3

what is recall bias

Answer 3

experimental subject gives false information

Question 4

what is observer bias

Answer 4

incorrect records

Question 5

what is detection bias

Answer 5

one group is examined more closely than the other group for outcome

Question 6

what is latency and accumulation effects

Answer 6

failure to account for induction period of a disease and the fact that dose accumulation can have an increased effect

Question 7

what is volunteer/self selection bias

Answer 7

people are more likely to participate in a study they have more concern about

Question 8

what is referral bias

Answer 8

ex: people have to be referred by primary care to a specialist who recruits them into a study

Question 9

what is healthy worker bias

Answer 9

people with jobs tend to be healthier than those without (exposed group may be more healthy than the unexposed group)

Question 10

what are the 3 ways in which we can control for confounders in the design

Answer 10

randomization
restriction
matching

Question 11

how can we control for confounders in analysis

Answer 11

stratified analysis

Question 12

why are prospective cohort studies more reliable than retrospective

Answer 12

you eliminate the chance of recall bias

Question 13

what bias is most significant in case control studies

Answer 13

recall bias

Question 14

in case control bias, are incident or prevalent cases better to use

Answer 14

incident

Question 15

what type of bias may result from using prevalence instead of incidence cases for a case control study

Answer 15

late look bias (the most severe cases may have died
or the least severe cases may not have come to the hospital so they may not be included in the study)

Question 16

in case control studies, what are hospital controls

Answer 16

patients at the same hospital as the case but with a different diagnosis

Question 17

what are 3 considerations for choice of hospital controls

Answer 17

1. the illness in the controls should be unrelated to the exposure of interest in the study
2. the illness in the controls should have the same referral pattern as the case
   hospital controls tend to avoid recall bias, and are cheaper/easier to recruit

Question 18

what is Berkson’s bias

Answer 18

when hospital controls in a case control study are used and the disease in controls related to the exposure of interest

Question 19

late look bias is also known as ___

Answer 19

Neyman bias

Question 20

in case control studies, what is overmatching

Answer 20

matching cases/controls on factors not thought to be relevant to the exposure-disease relationship

Question 21

when matching in case control studies, what do we not want to match

Answer 21

the exposure or the disease

Question 22

how does case crossover work

Answer 22

we take a case and look at a time in the past when they were not a case. we then measure the rate of exposure when they became a case, take another time in the past, and compare

Question 23

what are randomized control trials used for

Answer 23

to determine whether treatments improve prognosis, cure disease, or prevent disease

Question 24

what are historical controls

Answer 24

we compare the outcomes of patients provided with treatment in the present with the outcomes with the same diagnosis in the past

Question 25

what is simple radomization

Answer 25

we have a population of study participants, and 2 arms of the study. we randomize half of the participants to each arm

Question 26

what is stratified randomization

Answer 26

accounts for the fact that even after randomization, we still may end up with groups nonrepresentative of each other by chance (account for confounders)

Question 27

what is cluster randomization

Answer 27

sorts based on clusters if we are concerned that the intervetion will spread

Question 28

when are non-randomized historic controls used

Answer 28

when we have a small case number with a high case fatality rate

Question 29

what is the Hawthorne effect

Answer 29

people change their behavior because they know they are being studied

Question 30

single blinded studies help control for what

Answer 30

placebo effect
Hawthorne effect

Question 31

double blinded studies help control for what

Answer 31

observer biases such as the pygmalion effect and researcher expectancy

Question 32

what is the pygmalion effect

Answer 32

where investigators communicate to or influence patients so that the patients end up having the outcomes they are supposed to have

Question 33

what is a crossover trial

Answer 33

when participants start in one group and are moved to another treatment group

Question 34

what is the intention to treat analysis

Answer 34

we analyze the results based on the assigned treatment group

Question 35

what is the function of factorial design

Answer 35

it allows us to see if two treatments are more effective together than separately

Question 36

what is a type I error

Answer 36

we conclude treatments are different when in reality they are not (the null hypothesis is true but we thought the alternative hypothesis was true)

Question 37

what is a type II error

Answer 37

we conclude treatments are not different when in reality they are (the alternative hypothesis is true but we thought the null hypothesis was true)

Question 38

is type I or II error worse

Answer 38

I

type I- you think you found something but you actually didn’t

type II- you’re looking for something and you can’t find it so you keep looking

Question 39

how does alpha differ from beta in terms of type I vs type II error

Answer 39

alpha- probability of making a type I error
beta- probability of making a type II error

Question 40

what does the power of a study tell us

Answer 40

how capable a study is of determining that two treatments differ in their effectiveness when in fact they do differ

Question 41

what is the equation for power

Answer 41

1-beta

Question 42

an underpowered study is when the power is __

Answer 42

less than 80%

Question 43

how does the difference between cure rates in treatment groups help to determine the number of people needed to be recruited to maintain high power

Answer 43

a small the difference between the cure rate, the more people that need to be recruited

Question 44

what are the main functions in each stage of a clinical trial

Answer 44

I (in patient)- determine maximum tolerated dose, pharmokinetics, and pharmodynamics
II (outpatient)- establish how well the treatment worse and establish dose levels
III (multisite)- spread to diverse populations to generalize results
IV- post-FDA approval, surveillance for adverse effects

Question 45

in clinical trials, what is the function of the sponsor (holder of drug patent)

Answer 45

write protocol
select doctors to conduct research
determine research questions

Question 46

who are the primary kind of organization that conducts clinical research trials

Answer 46

contract research organization

Question 47

when can generic forms of a drug be sold

Answer 47

once the patent expires

Question 48

what are the 4 requirements for a generic drug to be produced

Answer 48

same active ingredients
inactive ingredients can be different but must be safe
same dosage form (tablet vs capsule, etc)
same route of administration
same pharmokinetics

Question 49

what is a nested case control study

Answer 49

you take a sample of those with disease and another sample from the population of those who have the disease and compare past exposure