PPD - Research (Sedgwick)

Question 1

Outline the aims and objectives of quantitative research in the clinical, biomedical and healthcare sciences (5)

Answer 1

Study health / illness in people
Develop safe and effective treatment
Build knowledge for better health / care
Pre-clinical research
Findings that can be generalised to particular populations through clear sampling / methodology

Question 2

Describe briefly the design and purpose of experimental and observational clinical studies, including randomised controlled trials and cohort studies

Answer 2

Experimental - Researcher influencers and records effect of intervention
Study the effect of the interventions on each cohort (medicine or placebo)

Observational - No intervention, observe and record behaviour / symptoms / attitudes
Activities that are already occurring - you want to know if a common behaviour / activity is causing an issue

Question 3

Outline the rationale for, and approaches to, sampling in order to make inferences about a population

Answer 3

How do you define a population? Geographical, time period
Must identify characteristics of population and of sample and determine whether there is any value generalising results (either to population level or more widely)
Leads to sampling error

Question 4

Outline the design of cohort studies

Answer 4

Design basics - Prospective study, disease free cohort, analysis looks at whether or not they were exposed to the risk factor over the study time period and whether they go on to develop the disease or not

Question 5

Discuss the advantages (2) and disadvantages of cohort studies (4)

Answer 5

Advantages - prospective design (so you can look at timing of disease and risk factors), sampling of population
Disadvantages - Confounding, time/expense, bias from loss to follow up, NOT for rare diseases

Question 6

Outline the statistical assessment of the association between potential risk factors and diseases or conditions using risk, and discuss its application in clinical practice

Answer 6

Can use risk, relative risk, attributable risk to explain risk

Need to be careful about wording and implications in clinical practice (patient may understand risk as ‘I will get disease’)

Question 7

Outline the design of clinical trials (and the types of issues/bias different aspects of the methodology address)

Answer 7

Type of experimental study (where researcher deliberately influences events)
Sampling to minimise selection bias
Random allocation (to eliminate allocation bias, minimise confounding and facilitate blinding)
Use of placebo to ensure blinding and minimise both assessor and response bias

Question 8

Describe the components of patient response to treatment in clinical trials, and discuss the application in clinical practice

Answer 8

Natural epidemiology - people generally get better
Placebo effect - people feel the ‘effect’ of treatment regardless of type of treatment
Treatment effect - felt in treatment cohort only
Hawthorne effect - people respond to receiving attention

Need to think critically about why patients are responding to particular treatments (or not responding) - when analysing studies, need to assess data carefully to determine how effect the treatment actually is (is placebo just as effective?)

Question 9

Outline the process of statistical hypothesis testing

Answer 9

Define your null and alternative hypotheses
Obtain sample from population
Calculate value of test statistic specific to null hypothesis - and use this to derive P-vale that quantifies our belief to SUPPORT null hypothesis
Cut off value is P=0.05
If P is LESS than 0.05 - evidence to reject null in favour of alternative (NOT true or false)

Question 10

Type 1 vs Type 2 error in statistical hypothesis testing

Answer 10

Type 1: You reject your null hypothesis, but it is actually true in population
Type 2: You do not reject null hypothesis, but it isn’t true in general population

Can try to avoid by increasing sample size and improving sampling methods

Question 11

Discuss the merits of applying research results based on statistical hypothesis testing to clinical practice

Answer 11

P value tells you if there is a statistically significant difference BUT DOES NOT say anything about clinical importance or relevance

Question 12

Null hypothesis vs alternative hypothesis

Answer 12

Null - no difference exists between Intervention and control

Alternative - different exists between intervention and control (two options - int>con or int