Sampling

Question 1

Simple random sampling

Answer 1

• use sampling frame
• each items is assigned a number
• use random number generator
  “Lottery sampling”

Question 2

Systematic sampling

Answer 2

Strata at random item in the sampling frame

Pick every kth person ( decided by the number of results wanted)

Question 3

Stratified sampling

Answer 3

Population dived into groups strata and a simple random sample carried out in each group

Question 4

Quota sampling

Answer 4

Population divided into groups according to characteristics.
A quota of items/ people in each group is set to try and reflect the group’s proportion in the whole population.
Interviewer selects the actual sampling units

Question 5

Opportunity sampling

Answer 5

Sample taken from people who are available at the time of study, who meet criteria

Question 6

Advantages and disadvantages of simple random sampling

Answer 6

A:
Bias free 
Easy and cheap
Known chance of being selected 
D:
Not suitable when population size is large 
Sampling frame needed 
Bias can be introduced if sampling frame is not random

Question 7

Advantages and disadvantages of systematic sampling

Answer 7

A:
Simple and easy to use 
Suitable for large populations 
D:
Sampling frame needed 
Can introduce bias is sampling frame is not random

Question 8

Advantages and disadvantages of stratified sampling

Answer 8

A:
-reflects population structure
-guarantees proportional representation of group within population
D:
-population used clearly classified into distinct strata
-selection within each strata suffers from the same disadvantages as simple random sampling

Question 9

Advantages and disadvantages of quota sampling

Answer 9

A:
Allows small sample to still be representative of population
-no sampling frame
- easy and kinda cheap
-allows for easy comparison between groups
D:
-Non random sampling can introduce bias
-population must be divided which is costly and could be inaccurate
- more people = more money and time

Question 10

Advantages and disadvantages of opportunity sampling

Answer 10

A: 
-Easy to carry out 
-Inexpensive 
D:
Unlikely to provide 
A representative sample
Highly dependant on an individual researcher