Lecture 5

Question 1

Purpose of analytic studies

Answer 1

To test hypotheses regarding, for example,

causes of disease;
methods for prevention of disease; the effects of treatments such as vaccines

Question 2

experimental =

Answer 2

researcher actively intervenes

Question 3

observational =

Answer 3

testing a predefined claim, no researcher intervention

Question 4

replication

Answer 4

Responses vary among people. Replication allows us to separate out
true effects from chance effects.

do what you are doing to multiple people, increasing the number of samples

Question 5

control

Answer 5

Provides context for evaluating the effect of interest.
need to be able to compare without doing it

What would have happened without the intervention or exposure of interest?
trying to compare the thing we are interested in with people who have no been exposed to the thing as you are unable to do it to the same group
placebo group is a type of control group

Question 6

how easy/hard is causality to prove?

Answer 6

causality is very difficult to prove, especially impossible with a single study

Question 7

Designing a study to evaluate the effectiveness of something?

Answer 7

make sure the exposure group and control group are similar and control for all other sources

Question 8

Experimental studies

Answer 8

The researcher manipulates the conditions (intervenes in a natural process) and records the results.
The aim is to control all other factors to isolate the effects of the intervention.
Best way to study causation.
Randomisation can be used to ensure that effects of unmeasured factors are equalised across the intervention and control groups.
Experimental studies are common throughout science

Question 9

Randomisation

Answer 9

Randomisation can be used to ensure that effects of unmeasured factors are equalised across the intervention and control groups.

ensure we are randomly allocating individuals to treatment and control group to ensure both groups are similar/comparable in number of each group in the treatment and the control group

Question 10

What is the best way to study causation?

Answer 10

Doing a experimental study ]

Question 11

Types of analytic study

Answer 11

Experimental

Observational

Question 12

Observational studies

Answer 12

The investigator does not intervene, simply observes a naturally occurring process, and collects information.

The idea is to get as close as possible to the information that would have been obtained if the experimental study could have been done.

Still aiming to test a particular claim, get as close to an experimental without doing one. Cannot always complete an experimental study because of money, ethics, time etc.

Question 13

Gold standard analytic study in research =

Answer 13

randomised control trials

Question 14

what do you compare in an RCT?

Answer 14

compare the 2 rates of a variable in the two different groups

Question 15

cohort study selection

Answer 15

participants are identified from population, questioned about variable, participants are effectively self selecting therefore the potential for confounding is a real danger (randomisation usually minimises this)

Question 16

case control study selection

Answer 16

analytic

start with disease and look back in time/start with disease of interest then figure out the treatment background, recall bias as people may not remember

Question 17

studies that are prospective

Answer 17

cohort study
randomised control trial

prone to loss to follow up

Question 18

studies that are retrospective

Answer 18

case control study

Question 19

experimental analytic studies ….

Answer 19

RCT

Question 20

observational analytic studies …

Answer 20

cohort

case control

Question 21

Randomised control trial

Answer 21

There are two important characteristics of a RCT:
1 Randomisation - or random allocation, is used to create two comparable groups, one who will have the placebo treatment and the other the experimental treatment. At the end of follow-up any difference between the groups can be attributed to the difference in treatment.
2 Control group - is used to isolate the effects of the intervention.
Blinding refers to not knowing whether the participant is in the intervention or the control group. Several people may be blinded to the allocation including the participants, the people caring for patients, the people measuring outcomes, the lead researcher.

researcher controls treatment and control group and assigns participants to them using randomisation

Question 22

blinding

Answer 22

Blinding refers to not knowing whether the participant is in the intervention or the control group. Several people may be blinded to the allocation including the participants, the people caring for patients, the people measuring outcomes, the lead researcher.

Question 23

single blinding =

Answer 23

only participants do not know, researchers know

Question 24

double blinding =

Answer 24

researcher also doesn’t know as well as participant

Question 25

Advantages of RCT

Answer 25

Experiment – the best way to test an hypothesis.

If the trial is well conducted, differences in outcome can be attributed to the intervention. (proof comes after decades of research of the same question)

Question 26

Disadvantages of RCT

Answer 26

May not be ethical or feasible.

expensive

Question 27

cohort study

Answer 27

Observational study, generally carried out to test hypotheses.

Characteristics of a cohort study:
Participants are selected before disease has developed.
Followed over time to determine development of disease.
Information is collected about exposures at baseline and during follow-up.
Cohort studies do have a control group, but allocation isn’t randomised there is always the potential for confounding. - effectively sell select, already exist in their two groups

Question 28

Cohort study advantages

Answer 28

Closest observational study to randomised controlled trial. Good for examining common outcomes.
Can evaluate the effect of exposure on multiple outcomes.

Question 29

Cohort study disadvantages

Answer 29

Long duration needed if the disease takes a long time to develop after exposure.
If the disease is rare, the number of participants needs to be very large. It is very hard (if not impossible) to remove all the effects of confounding.

Question 30

case control study

Answer 30

Observational study, generally carried out to test hypotheses

Characteristics of a case-control study:
Participants are chosen on the basis of their disease status: a group with disease (cases) and a group without (controls).
Information is collected from people with and without disease about exposures that occurred in the past (retrospective).

Question 31

Case control advantages

Answer 31

Relatively quick.

Smaller than cohort studies, particularly for rare diseases. Can examine the effects of multiple exposures.

Question 32

Case control disadvantages

Answer 32

Events have already occurred so the potential for bias is higher. It is very hard (if not impossible) to remove all the effects of confounding.