quantitate study design - critial numbers 1

Question 1

what do descriptive statistics do

Answer 1

describe a sample

Question 2

what do inferential statistics do

Answer 2

make inferences about our population

Question 3

how can a sample be biased

Answer 3

when certain subgroups from the target population are over/under represented

it arises when imperfections in the research process cause our findings to deviate from the truth

Question 4

what makes results generalisable

Answer 4

when the sample represents the population of interest

Question 5

what does bias impact

Answer 5

the validity and reliability of study findings

Question 6

what are the 5 types of bias

Answer 6

sampling bias
recall bias
information bias
the ‘hawthorne’ effect
attrition bias

Question 7

define sampling bias

Answer 7

when the sample does not represent the population of interest

Question 8

define recall bias

Answer 8

when there is inaccurate recall of past events/exposures/behaviours

Question 9

define information bias

Answer 9

when there is incorrect measurement eg miscalibrated machine

Question 10

define the ‘hawthorne’ effect

Answer 10

when participants change their behaviour when they know they are being observed

Question 11

define attrition bias

Answer 11

when there is differential dropout from studies eg sicker participants drop out so our outcome is only measured on healthier participants

Question 12

what are confounding variables

Answer 12

they obscure the real-life effect of exposure on an outcome

a confounder is related to both exposure and outcome

but is not on the causal pathway

Question 13

what are the 2 types of study designs

Answer 13

experimental
observational

Question 14

what is an experimental study design

Answer 14

when the researchers have intervened in some way

Question 15

what is an observational study design

Answer 15

when the researchers have not intervened, and have merely observed

Question 16

what are the 3 types of observational studies

Answer 16

retrospective - looking back into the past

cross-sectional - a single snapshot in time

prospective - following up over time

Question 17

what are randomised controlled trials

Answer 17

when participants are randomly allocated to different interventions and follow up

Question 18

what are 4 variations on the standard randomised controlled trial design

Answer 18

cluster randomised trials
crossover trials
multi arm and factorial trials
adaptive design trials

Question 19

what are cluster randomised trials

Answer 19

when participant sare randomised in grooups rather than indivusally

Question 20

what are crossover trials

Answer 20

when participants receive both interventions in a randomised order

Question 21

what are multi arm and factorial trials

Answer 21

when two or more interventions are evaluated in a single study

Question 22

what are adaptive design trials

Answer 22

when accruing information is used to inform planned design adaptations

Question 23

what are 4 variations on the standard randomised controlled trial design

Answer 23

cluster randomised trials
crossover trials
multi arm and factorial trials
adaptive design trials

Question 24

give 4 pros of randomised control trials

Answer 24

• gold standard
• reduces potential for confounding
• reduces bias via control and blinding
• can determine causal effects

Question 25

give 3 cons of randomised control trials

Answer 25

- can be unfeasible or unethical - require expert management - expensive

Question 26

what are cohort studies

Answer 26

non randomised observational typically prospective

Question 27

give 3 pros of cohort studies

Answer 27

- useful when random allocation not possible - can work for rare exposures - select participants on the basis of exposure - can examine multiple outcomes

Question 28

give 3 cons of cohort studies

Answer 28

- may require long follow up - can be expensive - not ideal for rare outcomes

Question 29

what are case control studies

Answer 29

non randomised observationall retrospective

Question 30

give 3 pros of case control studies

Answer 30

- faster because use past data so don't need long follow up - useful for rare outcomes - select participants on the basis of outcome - cheaper

Question 31

give 3 cons of case control studies

Answer 31

- more prone to bias or poor quality data - harder to show causal relationship - not ideal for rare exposures

Question 32

what are cross-sectional studies

Answer 32

non randomised observational single time point

Question 33

how do cross-sectional studies work

Answer 33

1 sample, 4 outcomes --> unexposed, outcome unexposed, no outcome exposed, outcome, exposed, no outcome

Question 34

give 3 pros of cross sectional studies

Answer 34

- relatively quick - cheap - can assess multiple exposures/outcomes

Question 35

give 3 cons of cross sectional studies

Answer 35

- susceptible to bias - cannot prove causality - not ideal for rare exposures/outcomes

Question 36

what are ecologolical studies

Answer 36

when the unit of observation is a group rather than an individual

Question 37

give 2 pros of ecological studies

Answer 37

- large scale comparisons - can quantify geographical or temporal trends

Question 38

give 2 cons of ecological studies

Answer 38

- ecological fallacy - cannot make inferences at the individual level

Question 39

what is the hierarchy of evidence from best to worst

Answer 39

1) systematic review/meta-analysis 2) randomised control trials 3) cohort studies 3) case control studies 4) cross sectional studies 5) case studies/ expert opinion/ anecdote

Question 40

how do cross-sectional studies work

Answer 40

1 sample 4 outcomes -->

Question 41

how do case control studies work

Answer 41

1 sample --> divides into cases and controls cases --> exposure controls --> exposure

Question 42

how do cohort studies work

Answer 42

1 sample --> divides into exposed and unexposed exposed --> outcome unexposed --> outcome

Question 43

how do randomised controlled trials work

Answer 43

1 sample --> divided into intervetion an comparator intervention --> outcome comparator --> outcome