Sampling methods

Cenus - disadvantages

Time-consuming, expensive
Cannot be used when testing process destroys item
Hard to process large quantity of data

Sample - advantages

Less time-consuming & expensive
Fewer ppl have to respond
Less data to process

Sample - disadvantages

Less accurate data
Sample not large enough to give info on small sub-groups

Simple random - advantages

Free of bias
Easy and cheap for small populations
Each sampling unit has known & equal chance of selection

Simple random - disadvantages

Not suitable for large population size
Sampling frame needed

Systematic - advantages

Simple & quick to use
Suitable for large populations

Systematic - disadvantages

Sampling frame needed
Can introduce bias if sampling frame not random

Stratified - advantages

Sample accurately reflects population structure
Guarantees proportional representation of groups

Stratified - disadvantages

Population must be clearly classified into distinct data
Selection within each stratum - same as random sampling

Quota - advantages

Allows small sample to be representative of whole
No sampling frame required
Easy comparison between different groups within a population

Quota - disadvantages

Non-random sampling can introduce bias
Dividing into groups - costly/ inaccurate
Increasing scope of study increases number of groups
Non-responses are not recorded

Opportunity - advantages

Easy, inexpensive

Opportunity - disadvantages

Unlikely to provide representative sample
Highly dependent on individual researcher