What is it?
Sampling is a means
by which a small group of items (the sample), are taken from a larger
group (the population), so as to be representative of the larger group.
When to use it
- Gathering data
- Analysing data
- Implementing
and testing solutions
- Ensuring continuous
improvement
What does it achieve?
Careful sampling
enables inferences to be made about the whole population, using the
results obtained from the sample. The precision of results derived from
the sample can be judged.
Most large groups
(populations) from which data are required are far too large to take
information from each individual item. However, a small group (sample),
if designed carefully, can represent the total population.
Inferences can be
drawn about the population from the data obtained from the sample.
Key steps
- Identify the
population
- Choose a sample
size
- Determine sampling
technique
- Simple random
sample
- Stratified
sampling (layer)
- Cluster sampling
(group)
- Systemic
sampling (systematic, every third unit etc.)
- Quota sampling
(proportional share)