SAMPLING

~RANDOM~

→ a sophisticated form of sampling in which all members have an equal chance of selection

Method:

  1. Obtain a complete list of all members of the target population

  2. Assign all the names on the list, a number

  3. Use the lottery method to select participants

+ Strengths

  • free from researcher bias

- Limitations

  • time-consuming

~SYSTEMATIC~

→ every nth member of the target population is selected

Method:

  1. A sampling frame is produced (which arranges the list of people into a set order)

  2. A sampling system is nominated

+ Strengths

  • avoids researcher bias

- Limitations

  • time-consuming

~STRATIFIED~

→ composition of the sample reflects the proportion of people in certain sub groups within the target population

Method:

  1. The researcher first identifies the different strata that make up the population (e.g. hair colour).

  2. The proportions are worked out for the sample to be representative

  3. Random sampling is used

+ Strengths

  • no researcher bias

  • can generalise findings

- Limitations

  • complete representativeness is not possible

  • can be time-consuming

~OPPORTUNITY~

→ anyone who is willing and available to take part will be selected

Method:

  1. Researcher asks anyone around at the time of the study, if they would like to take part.

+ Strengths

  • convenient

  • less costly

- Limitations

  • researcher bias

  • data is unrepresentative of the target population as participants are drawn from one specific area

~VOLUNTEER~

→ participants select themselves to be part of the sample

Method:

  1. Researcher may place an advert in a newspaper, inviting people to take part.

+ Strengths

  • requires minimal input from the researcher

  • time-efficient

- Limitations

  • volunteer bias