Sampling

Question 1

what is a sample?

Answer 1

a group used to represent a population

Question 2

what are the 5 types of sampling?

Answer 2

1. random
2. systematic
3. quota
4. cluster
5. stratified

Question 3

what is random sampling?

Answer 3

using a random number generator

Question 4

what is systematic sampling?

Answer 4

every nth person is selected

Question 5

what is quota sampling?

Answer 5

• convenience

- filling up a number

Question 6

what is cluster sampling?

Answer 6

• divide people into groups (usually geographically)
• each group = cluster
• clusters randomly selected

Question 7

what is stratified sampling?

Answer 7

• divide population into smaller groups (e.g. age)

- take a random sample of each

Question 8

what are the types of bias involved in sampling?

Answer 8

1. sampling bias
2. recall bias
3. social desirability
4. confirmation bias
5. volunteer bias

Question 9

what is sampling bias?

Answer 9

non-representative sample

Question 10

what is recall bias?

Answer 10

lack of specifics

Question 11

what is social desirability?

Answer 11

lie about things for social reasons

Question 12

what is confirmation bias?

Answer 12

interprets new evidence as confirmation of existing beliefs

Question 13

what is volunteer bias?

Answer 13

volunteers unlikely to be representative

Question 14

what are the types of bias involved in screening?

Answer 14

1. selection bias
2. lead-time bias
3. length-time bias

Question 15

what is selection bias?

Answer 15

participants selected are unlikely to be representative

Question 16

what is lead-time bias?

Answer 16

overestimating the apparent time surviving with a disease by bringing forward the time of diagnosis

Question 17

what is length-time bias?

Answer 17

overestimating the survival duration due to longer-living people being more likely to be picked up during screening

Question 18

what are confounders?

Answer 18

• related to outcome and exposure

- may affect results so need to be taken into account

Question 19

what is critical appraisal?

Answer 19

assessing reliability
- how consistent are the results of the study?
- is it repeatable?
assessing validity
- does the test investigate what it is meant to?

Question 20

how would you generate a research question?

Answer 20

PICO 
P - patient of population (exposure)
I - intervention
C - control 
O - outcome