Week 5 Textbook Chapter 4 Flashcards
(24 cards)
How is a target population defined?
Through inclusion and exclusion criteria.
What is the difference between probability and non probability sampling?
Random selection
What do sample statistics do?
Estimate populations parameters of characteristics, processes and behaviours.
What are sampling frames? Use?
List all elements in the target populations. Used to select cases.
What are the two types of sampling errors?
1) random sampling error 2) systematic sampling error
What does CLT stand for?
Central Limit Theorem
What is the EPSEM principle?
Each element in the target population has a known, equal and nonzero probability of selection.
What are the benefits of random selection?
1) Increases representativeness 2) Improves generalisability of findings
Probability sampling: simple random sampling?
Uses a lottery or random number table method to select elements numbered sequentially.
Probability sampling: systematic random sampling?
Uses a sampling ratio, interval and random start to select every kth element in the sampling frame.
Probability sampling: stratified random sampling?
Divides the target population into strata based on 1) key characteristics 2) an equal number of elements are selected from each stratum
What is the difference between Proportionate and Disproportionate stratified random sampling?
Use different sampling fractions to resemble (proportionate) or differ (disproportionate) from the proportion fond in the target population.
How does cluster sampling work?
Randomly selects naturally groups (clusters) and elements within the chosen clusters.
PPS Cluster sampling?
Clusters are selected based on the number of elements in each one.
Non-probability Sampling: Convenience sampling?
Chooses samples based on their accessibility.
Non-probability Sampling: Purposive Sampling?
Uses researchers knowledge and judgment to select cases.
Non-probability Sampling: Quota Sampling?
Select cases based on characteristics proportionate to what exists in the population.
Non-probability Sampling: Snowball Sampling?
Uses informants to make referrals to the next participant.
What determines sampling error?
1) heterogeneity of the population 2) sample size 3) confidence level
What is a confidence level?
Indicator of the probability that the true population parameter lies within the confidence interval values (two set–high and low)
Standard Error?
Calculates the standard deviation value (shows how well the sample mean estimates the population mean).
How to reduce sampling error generally?
Get a larger sample.
When is a large sample required generally?
1) heterogeneous populations 2) higher confidence levels (if comparing subgroups) 3) when there are a large numbers of variables
What are the ethical considerations of sampling?
1) voluntary and informed consent 2) take care with vulnerable populations 3) guarantee anonymity 4) be transparent when reporting results
