Sampling Types

Question 1

Simple random sampling

What is it
Cons

Answer 1

Items chosen by random procedure like

• drawing tickets out of box
• assigning numbers and use random number generator to do

Key fact is every sample has same POSSIBILITY OF BEING CHOSEN

2. Hard to do as it is unrealistic and may not have a list of every member in population (like might not know all the whales )

Question 2

Cluster sampling

Answer 2

Where population is divided into reasonably representive subgroups, and you just sample individually form here

So like yr 11, can do samples from different yr 11 schools

Can dinky do if this fact doesn’t affect anything , so not affected by school student attends

Question 3

Opportunity sampling

Answer 3

Like getting someone off the street

Advantage = easy quick cheap etc
Disadvantage = bias

Question 4

Stratified sampling

Answer 4

So population divided into DIFFERENT GROUPS such as age , gender etc, and then sampling is then within these groups.

If this is proportional then it it is proportional stratified sampling

+ representative of the population
- but might be hard to get strata representative of the population

Question 5

Quota sampling

Advantage disadvantage

Answer 5

Here you need to specify the NUMBERS OF data items sampled before , whereas in stratified this isn’t set but normally random .

Used In interviews

+ cheap quick and easy to do aswell as you fill up numbers
-likely to be biased (btec opportunity )

Question 6

Self selected sample

Answer 6

Here someone volunteers to do sample, like survey

Bias

Question 7

Systematic

Advantage disadvantage

Answer 7

A method is used to generate people to sample , like every tenth person in alphabetical order

+represntjve
- needs to be sorted in a way first