Sampling Techniques
Population vs. Sample
A population is the entire set of people you want to study
It can be large, like a religion, or a culture
It can be smaller, like a town, a denomination, or a subculture
A sample is a smaller set from that population
If all members of a population participate, then you do not have a sample, you have a census
Biased or Representative
Biased samples are when certain members of a population have a higher chance of being
included in the sample
Representative sample is when all members of population have an equal chance of being
selected to participate
A representative sample is required for EXTERNAL VALIDITY
Biased Sampling Techniques
What might give certain members of the population a higher chance of being included in the
sample?
THOSE WILLING TO DO IT: What type of people respond and what type of people
don’t respond?
AAU study had a biased sample because victims were more likely to respond
THOSE EASILY ACCESSED: How homogenous is the group you have access to? Might
there be observer bias or oberserver effects?
Example: professero surveying their own students, especially if giving survey on one
day which is biased toward those who come to class frequently
THOSE CHERRY-PICKED: What quality makes the researcher choose a particular
group?
Example: professor surveys one class and not all of his classes
Biased (Non-Probability) Sampling Techniques
Convenience sampling – using people who are readily available or willing to participate
Population vs. Sample
A population is the entire set of people you want to study
It can be large, like a religion, or a culture
It can be smaller, like a town, a denomination, or a subculture
A sample is a smaller set from that population
If all members of a population participate, then you do not have a sample, you have a census
Biased or Representative
Biased samples are when certain members of a population have a higher chance of being
included in the sample
Representative sample is when all members of population have an equal chance of being
selected to participate
A representative sample is required for EXTERNAL VALIDITY
Biased Sampling Techniques
What might give certain members of the population a higher chance of being included in the
sample?
THOSE WILLING TO DO IT: What type of people respond and what type of people
don’t respond?
AAU study had a biased sample because victims were more likely to respond
THOSE EASILY ACCESSED: How homogenous is the group you have access to? Might
there be observer bias or oberserver effects?
Example: professero surveying their own students, especially if giving survey on one
day which is biased toward those who come to class frequently
THOSE CHERRY-PICKED: What quality makes the researcher choose a particular
group?
Example: professor surveys one class and not all of his classes
Biased (Non-Probability) Sampling Techniques
Convenience sampling – using people who are readily available or willing to participate
