Quantitative Research Evidence

Question 1

What is the difference between quantitative and qualitative?

Answer 1

Quantitative

• Generalisation
• Concise and narrow focus
• Theory driven
• Begins with a hypothesis (hypothesis testing/confirmatory)
• Requires greater number participants

Qualitative

• Contextualisation
• Complex and broad focus
• Data driven
• Hypothesis generating (exploratory)
• Requires fewer participants

Question 2

If researchers assign participants to receive different treatments (exposures) is it experimental or observational?

Answer 2

Experimental

Question 3

What is a cohort study?

Answer 3

• Looks forward in time
• Investigator identifies groups that differ according to the exposure of interest e.g. group with healthy BMI vs increased BMI. Groups are then followed forward in time to determine if they differ in relation to outcome of interest e.g. heart disease.

Question 4

What is a case control study?

Answer 4

Looks back in time to investigate exposures that caused outcome. e.g. people with heart disease and without HD (control) and see if they differ in terms of exposures

Question 5

What is a cross-sectional study?

Answer 5

• Snapshot at one timepoint
• Looks at association between factors

Question 6

What is sampling?

Answer 6

The way in which a group of people are taken from a larger population

Question 7

What are inferential statistics?

Answer 7

Allows us to make inferences about the population from the results of a smaller sample

Question 8

What is a simple random sample?

Answer 8

Every individual in the populations has an even chance of being selected e.g. tossing a coin

Question 9

What is a systematic sample?

Answer 9

Performed by assembling the population into a numbered list, randomly selecting the starting point and then selecting individuals using a fixed interval

Question 10

What is a stratified sample?

Answer 10

Splitting population into smaller groups that have similar characteristics (strata). Then we randomly sample a proportional amount of individuals from each group. e.g. splitting by gender then selecting a proportion from each group

Question 11

What is a cluster sample?

Answer 11

When you have naturally occurring groups from which you wish to sample e.g. patients belonging to different GP surgeries

Question 12

What are the 4 types of non-probability sampling?

Answer 12

Convenience

Voluntary response

Purposive sample

Snowball sample

Question 13

What is a convenience sample?

Answer 13

Selecting individuals that are easy to reach e.g. survey to nursing students

Question 14

What is a voluntary response sample?

Answer 14

Researcher using adverts, and volunteers contact researcher. This bias’ the study

Question 15

What is a purposive sample?

Answer 15

Researchers specifically select participants based on characteristics they require in the study population

Question 16

What is a snowball sample?

Answer 16

Participants are asked to refer researcher to people just like them. Useful when studying hard to reach individuals e.g. drug users

Question 17

What is generalisability/external validity?

Answer 17

The extent to which the findings of a study can be applied to the population from which the study sampled. A sample should be representative of the population to ensure generalisation

Question 18

What is an exposure?

Answer 18

Any factor that may be associated with an outcome of interest

e.g. smoking -ve exposure; exercise +ve exposure

Question 19

What is an outcome measure used for?

Answer 19

Used to assess the effect, both positive and negative of an intervention. Quantitative outcome measures can be both objective and subjective.

• Objective - blood pressure, white cell count (not open to outside influence)
• Subjective - visual analogue scale for rating pain (patient reported outcome)

Question 20

What is data collection?

Answer 20

The process of conducting the outcome measures and recording results.

Question 21

What is a randomised controlled trial?

Answer 21

• A study in which a number of similar people are randomly assigned to 2 or more groups to test a specific drug, treatment or other intervention.
• One group has drug, other has placebo/control/other intervention
• Groups followed up to see how effective the experimental intervention was
• Outcomes measured at specific times
• This method reduces bias

Question 22

How does randomisation work?

Answer 22

• Individuals are assigned to different groups in a random manner e.g. random numbers table or computer generated sequence
• Each person has the same chance of receiving each intervention.
• Attempts to create groups that are similar at baseline
• Differences in outcome measures at the end of the study can be attributed to the intervention

Question 23

Why is stratified randomisation used?

Answer 23

Used to create treatment groups with similar characteristics

Particularly useful when certain characteristics are though to affect response to the intervention

Question 24

What is allocation concealment

Answer 24

Concealment of which group each participant will be assigned to

Prevents selection bias

Neither investigators nor participants know groups

Question 25

Single vs double blinding

Answer 25

Single - Patients prevented from discovering which treatment they are receiving

Double - Patients and investigators prevented from discovering which treatment they are receiving

Question 26

When would you conduct a non-randomised control trial?

Answer 26

• Random allocation inappropriate or not possible
• Failure to ensure true randomisation

Question 27

What are the advantages and disadvantages of non-randomised controlled trials?

Answer 27

• Advantages - allowing for participant preference can improve adherence and reduce drop out rates
• Disadvantages - Cannot control for confounding factors; increased risk of selection bias (If groups are so different at start of trial, results of study cant be reliably attributed to the intervention being investigated

Question 28

What is an observational study?

Answer 28

When the exposure is not assigned, it is observed