evidence of health population 2

Question 1

define a randomised control trial

Answer 1

You randomly allocate the study population into 2 groups- treatments and the control group.
Measure the rate of outcome.

Question 2

what is a single blinded trial

Answer 2

patient doesn’t know whether they are having the treatment or not.

Question 3

what is a double blinded trial

Answer 3

neither the patient nor doctor knows who has the treatment or not- avoids doctor bias.

Question 4

define placebo

Answer 4

is where you are given an alternate treatment to that which works but patients still report a positive or negative effect of it possibly.

Question 5

what is observers bias

Answer 5

that the individual analysing the situation is more likely to be inclined / biased in interpreting the results in favour of the trial e.g. the drug works.

Question 6

what are the pros of a randomised control study

Answer 6

Strongest evidence for causality.
If randomised, selection bias and confounding removed.
If blinded less observer bias.

Question 7

what are the cons of a randomised control study.

Answer 7

Not real life
High cost
Inappropriate/Unethical for many research questions.

Question 8

define error

Answer 8

things, which are incorrect but should be correct.

Question 9

when can error occur in a study

Answer 9

study design
data collection
data management
data analysis
laboratory analysis
sample collection
study design

Question 10

define selection bias

Answer 10

choosing the wrong people e.g. men in a cervical cancer case controlled study

Question 11

when does self selection arise

Answer 11

may come about when subjects make decisions.

Participants contact study e.g. through adverts or word-of-mouth
More likely to participate due to family history
Healthy-worker effect’ – workers self-selecting as more likely to be healthier as they remain at work; unwell workers retire.

Question 12

define information bias

Answer 12

collected the right people but collected the wrong measure from the subjects.

Question 13

define recall bias

Answer 13

Different view points given of information due to different recall given by different subjects.

Question 14

define interviewer bias

Answer 14

A partiality towards a preconceived response based on the structure, phrasing, or tenor of questions asked in the interviewing process.

Question 15

define surrogate bias

Answer 15

obtain information from person other than subject

Question 16

what is the worst to best study

Answer 16

1. Anecdote
2. Cross sectional
3. Ecological
4. Case controlled
5. Cohort
6. Randomised

Question 17

what are the main types of information bias

Answer 17

recall bias
interviewer bias
surrogate bias