L5 14/02

Question 1

For a randomised controlled trial or any experiment gathering new data, what form of data is relied on?

Answer 1

Quantitiative

Question 2

What are experimental designs?

Answer 2

• Dominant method in health research

- Used to test as hypothesis and explain variable relationships

Question 3

3 key features/assumptions of experimental designs

Answer 3

Objectivity, determinism, reductionism

Question 4

Objectivity definition

Answer 4

Reality exists beyond social construction and can be measured

Question 5

Determinism definiton

Answer 5

That the (health) world is governed by natural laws, which are predictable and can be generalised, reasons why everything happens

Question 6

Reductionism definition

Answer 6

The phenomena of interest can be reduced to standard units of measurement

Question 7

What are the 3 research validities?

Answer 7

Internal validity - the study design
External validity - sampling techniques, generalisability
Measurement validity - data collection methods

Question 8

Why are randomised control trials (RTCs) essential?

Answer 8

If the research is explanatory and needs to demonstrate a causal relationship between variables

Question 9

What do RCTs use to eliminate the effects of confounding variables and biases?

Answer 9

Probability sampling, random allocation, and blinding (people aren’t entirely sure which group they are in) to eliminate the effects of confounding variables and biases

Question 10

What do RCTs aim to do?

Answer 10

• The study design and procedures aim to control for all possible alternative explanations of observed changes in dependent variables

Question 11

What kind of studies are included in RTCs?

Answer 11

• Field experiments
• Cohort studies
• Case-control studies

Question 12

What are some threats to internal validity in quasi-experiments?

Answer 12

• History: events occurring between pre and post-test measures – only difference between pre and post should be the intervention
• Testing: the effect of repeated measures on subject responses
• Regression to the mean: equalisation of measures over time
• Instrumentation: changes in the measuring tools (or measurers)
• Selection and interaction biases
• Mortality: differential ‘drop-out’ rates – will affect ability of data to demonstrate causality

Question 13

What is a sample?

Answer 13

A subset of the population which it is feasible to study. A sample can also be the unit of analysis: a person, an organisation, a body part, anything. The sample is chosen to represent a population.

Question 14

Give 2 examples of sampling threats

Answer 14

• Sample bias (a population characteristic is over- or under-represented in the sample e.g., volunteer bias)
• Sample size (too small a sample gives false (unrepresentative) results, unable to make generalisations about whole population)

Question 15

Definition of random sampling

Answer 15

Drawing a specific number from a list of the whole population

Question 16

Definition of random allocation

Answer 16

• Assigning people in the sample into treatment and control groups
• Can use a random or non-random sample from the population
• Random number generator

Question 17

Definition of blinding

Answer 17

Where the subjects and / or the researchers do not know who is in the experimental and control groups e.g., placebo or drug

Question 18

Definition of double blinding

Answer 18

When BOTH subjects and researchers don’t know who is in which group

Question 19

3 types of experimental design

Answer 19

• Randomised control trials
• Cohort studies
• Case control studies

Question 20

RCTs aim to…

Answer 20

Eliminate bias and provide valid conclusions

Question 21

What are some key features of RCTs?

Answer 21

• Random allocation to groups
• Patients and researchers unaware of which treatment was given until the study completed (blinding)
• Both groups are treated identically except for the experimental treatment
• Analysis estimates the size of the difference in outcomes between groups AND the statistical power of the effect

Question 22

In quasi-experiments….

Answer 22

Participants are NOT randomized to treatment or control groups

Question 23

In cohort studies…

Answer 23

• ABA process
• Participants are studied over time
• The study population shares common characteristics

Question 24

In case control studies…

Answer 24

• Studies that address questions about harm or causation
• Compares different cohorts
• Investigates why some people develop a disease or behave the way they do vs others who do not

Question 25

What are 7 key factors to consider in experiments?

Answer 25

1. Recruitment methods
2. Sample size
3. Randomisation method
4. Controls and confounding factors
5. Blinding
6. Data collection methods
7. Validity of outcome measures

Question 26

What assumptions are relevant to all forms of experimental designs?

Answer 26

• Objectivity
• Determinism
• Reductionism

Question 27

Does a randomised controlled trial NOT require a placebo intervention?

Answer 27

False, it is a key attribute of RCT - it does require it

Question 28

Is internal validity in a RCT increased by use of randomisation and blinding?

Answer 28

Yes

Question 29

When participants in both intervention and control groups are unaware of which group they are in the study it can be described as double blinding?

Answer 29

No it cannot

Question 30

Does a field experiment GUARANTEE causality whereas a RCT can only INFER it?

Answer 30

No, a RCT can guarantee causality but field experiment can only infer

Question 31

Would a valid measurement tool will produce the same results on different occasions?

Answer 31

No, that’s reliability

Question 32

Does probability sampling decreases the chance of a sample being representative of the population?

Answer 32

No

Question 33

What are potential threats to the internal validity of an experimental design?

Answer 33

• Selection bias
• External events affecting pre and post testing
• Participant response to being tested