sampling techniques Flashcards
random sampling
a sophisticated method of ensuring all members of target population have an equal chance of being selected
systematic sampling
when every nth member of the target population is selected using a sampling frame
systematic sample method
- sampling frame produced. list of people in target population organised e.g. alphabetical order
- sampling system nominated (every 3rd, 6th, 8th person etc.) or interval determined randomly to reduce bias
- researcher works through sampling frame until sample complete
stratified sampling
a sophisticated method of ensuring that the composition of the sample reflects the proportions of people in certain sub-groups within the target population
stratified sample- method
- researcher identifies different strata that makes up target population
- proportions needed for sample to be representative calculated
- participants that make up each stratum selected using random sampling
opportunity sampling
people selected based on availability and willingness
volunteer sampling
participants select themselves to be part of the sample
random sample- strengths
- no researcher bias. no influence over who is selected so can’t choose those they think would support hypothesis.
random sample- weaknesses
- difficult and time-consuming. complete list of target population difficult to obtain.
- still may have unrepresentative sample (probability- still more representative than opportunity sampling)
- selected participants may refuse
systematic sample- strengths
- avoids researcher bias. once selection sample established no influence.
- usually fairly representative.
stratified sample- strengths
- avoids researcher bias. once sub-divided into strata, randomly selected numbers no influence
- representative sample, accurately reflects composition of population. generalisation of findings.
stratified sample- weaknesses
identified strata cannot reflect all ways that people are different. complete representation of target population not possible.
opportunity sample- strengths
- less time-consuming and more economical
opportunity sampling- weaknesses
- sample unrepresentative of target population. drawn from specific area.
- researcher bias. complete control over selection.
volunteer sample- strengths
less time-consuming, requires minimal input from researcher