RESS 3

Question 1

Why do we study healthcare practice?

Answer 1

1. Provide better quality evidence rather than guesswork

2. Primary + secondary studies allow results to generate guidelines, standards and targets

Question 2

Study types used in healthcare development and assessment

Answer 2

1. Research
2. Audit
3. Service Evaluation

Question 3

Wha does research allow us to do?

Answer 3

Generate new knowledge where there is no or limited research evidence available and which has the potential to be generalisable of transferable

Question 4

What is an audit?

Answer 4

A quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change

Question 5

What is a service evaluation?

Answer 5

Evaluates a proposed service or current practice with the intention of generating information to inform local decision making

Question 6

What method can be used to define the search terms used in research lit. searches?

Answer 6

PECOS

Patient
Exposure
Comparison
Outcome
Study design

Question 7

What are the competing priorities which clinical studies require us to balance?

Answer 7

1. design and conduct studies that provide the correct answer
2. maximise the efficient use of resources
3. comply with ethical and legal regulations

Question 8

What are the 4 potential sources of bias?

Answer 8

Sampling/selection bias
Measurement bias
Analytical bias
Dissemination bias

Question 9

How do each of the following study designs help address the issue of bias?

• cross sectional
• case control
• cohort
• trial
• meta analysis

Answer 9

• cross sectional: provides evidence of association within a sample
• case control: provides evidence of association between samples
• cohort: provides evidence of directionality of associations
• trial: provides evidence of causality
• meta analysis: provides evidence of reproducibility/generalisability

Question 10

What 3 ethical concepts came from the Belmont Report’s

Answer 10

Respect for persons
Justice
Beneficence

Question 11

What types of projects do not require formal ethical approval?

Answer 11

1. Secondary research
2. Non human research
3. Audit/Service evaluation
4. Service evaluation (collects info on existing service)

Question 12

What types of projects do require formal ethical approval?

Answer 12

1. Non human subjects/animals
2. Vulnerable groups
3. Experimental research
4. Non experimental research where information on more than only existing service delivery is required

Question 13

What is a sample?

Answer 13

A collection of data drawn from a population

Question 14

What is a target population?

Answer 14

The total finite population we wish to know about from which your sample is drawn

Question 15

What is the study sample?

Answer 15

The units/participants drawn from the target population that constitute our data set

Question 16

What are the types of samples?

Answer 16

Complete: all

Unstratified Random: every member of the target population has the same chance of being sampled

Stratified Random: randomly sample from target pop.

Question 17

Pros and cons of complete sampling

Answer 17

Pro: no bias introduced by design
Con: potentially expensive

Question 18

Pros and cons of unstratified sampling

Answer 18

Pro: easy to design and conduct
Cons: Smaller groups may be under represented by chance

Question 19

Pros and cons of stratified sampling

Answer 19

Pro: representative of population
Pro: unequal sampling of strata improves power for rare strata
Con: population may not be easily divisible
Con: strata may now be known until after sampling

Question 20

Why do we statistically analyse data?

Answer 20

Estimation

Hypothesis testing

Question 21

What happens to the confidence interval if the sample size is increased?

Answer 21

It decreases and becomes more reliable

Question 22

What does hypothesis testing tell you?

Answer 22

How unlikely you are to see an effect this big by chance is there is no genuine effect

Question 23

When is the association significant?

Answer 23

When the CI does not include the null at p=0.05.

Question 24

What is power?

Answer 24

The probability of rejecting the null hypothesis when the null hypothesis is false

Question 25

When is the power greater?

Answer 25

1. the mean effect is bigger 2. variation in effect is smaller 3. sample is bigger (the only one that can be influenced

Question 26

When should power be calculated?

Answer 26

Before a study to ensure it is well designed | After a study when no association is found - to demonstrate if the study was sufficiently powered

Question 27

What is the 'odds of an event'

Answer 27

= the probability an event occurs / probability that it doesn't occur

Question 28

What is the odds ratio?

Answer 28

The odds of an event for exposed / odds of an event for unexposed

Question 29

Which of confounders, competing exposures and mediators, are not adjusted for?

Answer 29

Mediators

Question 30

What are confounders

Answer 30

They cause both the outcome and exposure

Question 31

Why must confounders be adjusted for?

Answer 31

They will generate a statistical relationship between the outcome and exposure even when none exist

Question 32

What are mediators?

Answer 32

They cause the outcome and are caused by the exposure

Question 33

Whey are mediators NOT adjusted for?

Answer 33

They are part of the causal path between O and E so should not be adjusted

Question 34

What are competing exposures?

Answer 34

They cause the outcome but have no relationship with the exposure

Question 35

When would a competing exposure be adjusted for?

Answer 35

If they cause a substantial amount of the variation in the exposure

Question 36

A causal relationship can be:

Answer 36

1. functional 2. emperical 3. theoretical 4. speculative

Question 37

When is a causal relationship possible

Answer 37

Only when the cause variable precedes the effect

Question 38

What do prospective studies do?

Answer 38

Record variables over the study period, with the outcome measured subsequently

Question 39

What do retrospective studies do?

Answer 39

Measure the outcome and then look backwards to measure the exposure and other variables

Question 40

Pros and cons of prospective data collection

Answer 40

Pros: - fewer sources of bias - less chance of confounding - some data can only be measured prospectively Cons: - time and resource intensive - tendency to collect data on more variables than you need or can use in your analyses - subjects can drop out - usually unfeasible for rare outcomes

Question 41

Pros and cons of retrospective data collection

Answer 41

Pros: - data collection is less time and resource intensive - allows oversampling of rare outcomes Cons: - more susceptible to bias - some variables cannot be measured directly - if data are from records, little control over these

Question 42

What are some sources of measurement error?

Answer 42

Instability in the variable | Imperfect measurement

Question 43

What allows for a better line of best fit

Answer 43

Less residual variation

Question 44

What does linear regression allow?

Answer 44

Comparison of two variables

Question 45

What is R squared?

Answer 45

Proportion of variation explained by the linear model. Values closer to 1 = more of the variation is explained by the model

Question 46

What can R squared not calculate for?

Answer 46

Logistic regression

Question 47

What do the results of the odds ratio mean?

Answer 47

``` >1 = control is better than intervention <1 = intervention is better than control ```