week 5- sampling Flashcards
(40 cards)
What is sampling?
Process of selecting units to represent a population.
What does homogenous mean?
All members of a population are identical.
What does heterogeneous mean?
When individual members of a population are different from each other.
What are the consequences of a heterogeneous sample?
- May not accurately represent population.
- More heterogeneous, larger sample needed.
What is probability sampling?
- Each population element has a random chance of being sampled.
- Greater confidence that the sample is representative, so it’s more generalizable.
- Often more challenging and time consuming.
What is non-probability sampling?
- Each population element has a non-random and unknown chance of being sampled.
- Much less confidence that the sample is representative (less generalizable).
- More feasible.
What is convenience sampling?
- Subjects are selected because of their convenient accessibility and proximity to researcher.
- Can also be self-selection of individuals willing to participate.
What are the advantages of convenience sampling?
- Simplicity.
- Helpful for hypothesis generation.
- Data collection can be facilitated in short duration of time.
- Feasible.
What are the disadvantages of convenience sampling?
- Highly vulnerable to selection bias and influences beyond the control of the researcher.
- High level of sampling error.
- Little credibility.
What is quota sampling?
Researcher identifies a particular strata of the population and the quota sample proportionally represents the strata (e.g., age, gender, religion).
What is the difference between probability sampling and randomization?
- Probability sampling is a process for selecting study participants, happens before enrolment.
- Randomization is a process for assigning participants to study groups, happens after enrolment.
What is simple random sampling?
Randomly selected subset of a population, each member has an equal chance of being selected.
What are the challenges with simple random sampling?
- Have to have a complete list of the whole population.
- Have to be able to contact or access each member of the population if they’re selected.
- Can have time and resources to collect data from the necessary sample size.
What are the advantages of simple random sampling?
No bias, most likely to be representative of population.
What are the disadvantages of simple random sampling?
Time-consuming/inefficient, may be impossible if researchers can’t build a sampling frame.
What is stratified random sampling?
Members of population are grouped into homogenous subsets, samples are picked randomly within the subsets to match population distribution variables.
What are the advantages of stratified random sampling?
Increased representativeness, low risk of bias.
What are the disadvantages of stratified random sampling?
Variable info may not be available, time-consuming, expensive.
What is systematic sampling?
A random sample with a fixed periodic interval is selected from a larger population (e.g., every third person).
What are the advantages of systematic sampling?
Efficient and convenient.
What are the disadvantages of systematic sampling?
Easy to introduce bias.
What is cluster sampling?
Involves dividing population into clusters and then randomly selecting entire clusters for inclusion in the sample.
What are the advantages of cluster sampling?
Cost-effective, feasible for large populations.
What are the disadvantages of cluster sampling?
Higher sampling error, risk of bias.
