Unit 6: Business Decision Making - Sources for the collection of data
Sampling methods
There are various in which to take a sample from a population when undertaking a questionnaire.
Random Samples
- the sample is taken from the population purely at random
- use random number tables or the random number feature on spreadsheet programmes (eg Excel)
Quota Samples
- the proportions of people to be chosen are pre-set
- the quota chosen is representative of the population in one or two respects but not necessarily in others
- for example: people with blue eyes
Multi-Stage Samples
- a random sample of a random sample
- for example: to get a random population from 100 streets in Bristol, randomly select 10 streets from the 100 and then select 10 households form the 10 streets
Cluster Sampling
- same as multi-stage sampling with the final sampling done according to a specific characteristic
- for example: taking our ten streets, we would ask ten men with dark hair
Systematic Sampling
- the sample is undertaken by choosing the respondents at regular intervals,
- for example: taking every tenth street from our list of 100 streets and then every tenth household.
- these samples are biased against those people who have no chance of been chosen once the first person has been chosen
Stratified Sampling
- the population are divided into blocks where all members have something in common, random samples are then chosen from these blocks
- for example: splitting the population into blocks according to age
