Study design

Question 1

what does study design allow researchers to do

Answer 1

test hypotheses

Question 2

why is study design important

Answer 2

making sure correct and significant answers to research questions are achieved

Question 3

quantitative

Answer 3

numerical collected data

Question 4

qualitative

Answer 4

uses collected observation and textual data

Question 5

as the pyramid of evidence increases so does

Answer 5

rigor, quality, reliability

Question 6

information becomes

Answer 6

increasingly filtered and evidence based

Question 7

why is the tip narrow

Answer 7

there are far fewer studies which provide strong evidence

Question 8

types of study design:

Answer 8

• case report
• case control
• cohort
• RCT
• practice guidelines
• systematic review
• meta analyses

Question 9

case report

Answer 9

Case report
- Describes and evaluates individual cases, often unique cases of disease or condition
o Unexpected events that may yield useful information
o Cases where one or two subject have unexpected disease or disorders
- Often written as a detailed story
- Lowest level of evidence, but important first line of evidence
- Next step would be a case-control study- determine relationships between relevant variables

Question 10

positives of case reports

Answer 10

• Identification of new trends or diseases

- Can identify rare side effects to new drugs

Question 11

negatives of case reports

Answer 11

• Cases may not be generalizable

- Weak evidence and not based on systematic studies

Question 12

case-control

Answer 12

• Retrospective study
• Observational- no intervention is attempted
• Compares subjects with diseases or outcome of interest with subjects free of disease
• Looks back specific risk factors subjects have/are been exposed
• Determines the relationship between the specific risk factor and disease
• Used to estimate odds

Question 13

positive of case-control

Answer 13

• Less time needed to conduct study because outcome of interest has already occurred
• Multiple risk factors can be looked at
• Can establish association

Question 14

negatives of case-control

Answer 14

• Retrospective- relies on memory and data is exposed to recall bias- decreasing quality
• difficult to find suitable control group
• Won’t help find treatment
• Involves a certain ‘guessing’ element
• Doesn’t prove causation

Question 15

cohort studies

Answer 15

• Prospective study
• Contains one or more cohort (group of people with disease or outcome of interest)
• Evaluates disease, risk factors and outcomes
• As the study goes on, outcome of subjects in the cohorts are measured and specific characteristics are related to the outcome/ disease of interest.

Question 16

positives of cohort studies

Answer 16

• Subjects can be matched, which limits the influence of confounding variables
• Standardization of criteria is easy
• Cheaper than RCT

Question 17

negatives of cohort studies

Answer 17

• Cohorts hard to identify due to confounding variable
• No randomisation (imbalances in patients attributes)
• Blinding is hard
• Time consuming

Question 18

RCTs

Answer 18

• Gives strongest clinical evidence
• Randomly assigns participants into an experimental or control group
• Expected differences in outcome between control and experiment group should be in response to the intervention
• Often used in clinical trials- since helps prove causation

Question 19

positives of RCTs

Answer 19

• Randomisation takes away population bias
• Easier to blind than observational studies
• Statistical methods= easy to use

Question 20

negatives of RCTs

Answer 20

• Expensive- time and money
• Study population may not be representative of population as a whole
• Drop outs are common

Question 21

practice guidelines

Answer 21

• Outlines best current practice to aid healthcare professionals in making evidence based decisions
• Produced by a panel of experts
• Based on extensive review of literature

Question 22

positives of practice guidelines

Answer 22

+

• Based on published literature
• Supports evidence based decision for clinician

Question 23

negatives of practice guidelines

Answer 23

• Often outdated
• Not available for niche topics
• Expensive and time taxing

Question 24

systematic reviews

Answer 24

• Review of all relevant studies on a topic to answer a specific clinical/ health related question
• Summarises findings
• Comes to a combined conclusion

Question 25

positives of systematic reviews

Answer 25

• Uses all literature (unpublished studies included)
• Cheaper
• Less time consuming than a new study
• Means results from different studies can be generalised
• More reliable and accurate than individual studies

Question 26

negatives of systematic reviews

Answer 26

• Still time consuming

- Heterogeneity of studies may mean studies cannot be combine

Question 27

meta-analyses

Answer 27

• Subset of systematic review
• Combines qualitative and quantitative studies giving greater statistical power
• Combines results of papers to produce forest plots
• Establishes statistical significance of studies with conflicting results
• Meta-analyses using RCTs alone would produce the highest-level of evidence

Question 28

positives of meta-analyses

Answer 28

• Greater statistical power
• Data more relevant to population due to larger/ more varied sample
• Evidence based resource

Question 29

negatives of meta-analyses

Answer 29

• Time consuming
• Not all studies appropriate for inclusion
• Heterogeneity of study populations