Sampling Flashcards
Sampling
A small number of participants
Sample should be representative so that the results can be generalised to the target population
Random sampling
Each member of a population has an equal chance of being selected
• A list of all members of the target population is obtained.
• All of the names on the list are assigned a number.
• The sample is generated using some sort of lottery method (random number generator or picking names out of a hat).
Strength- random sampling
Free from bias
Limitation - random sampling
Time comes consuming
difficult to get a list of everyone unrepresentative may be refusal
Systematic sampling
When every nth member of the target population is selected from a sampling frame
Strength-Systematic sampling
Free from bias
Most representative
Limitation-Systematic sampling
Complete representation of sample is not possible • Time-consuming to conduct
• Participants might refuse to take part
Stratified sampling
•
The researcher then works out how many participants are needed
from each sub group to make up the sample. These participants are
picked out randomly.
Strength- stratified sampling
Free from researcher bias
• Produces the most representative sample
Limitation-stratified sampling
Complete representation of sample is not possible • Time-consuming to conduct
• Participants might refuse to take part
Opportunity sampling
Selecting anyone who happens to be willing or available to take part.
The researcher simply takes the chance to ask whoever is around at the time of their study
Strength- opportunity sampling
• Saves time
• Saves money
Limitation- opportunity sampling
• Unrepresentative sample – only people who are around at the time • Unrepresentative sample – only some people will say yes!
• Researcher bias occurs
Volunteer sampling
An advert is produced and individuals self select themselves to take part
It is also referred to as self-selection
Strength- volunteer sampling
• Easy
• Less time consuming
Limitation- volunteer sampling
Volunteer bias occurs – unrepresentative sample
