Week 2 Flashcards
What is target population
People you want your results to apply to
What is source population or sampling frame
People from whom the population is selected
What is the sample
People approached to take part in the survey
What is the study population
People who actually took part in the survey
What are the 4 types of proability sampling
- Simple random sampling
- Stratified random sampling
- Cluster sampling
- Multistage sampling
What is simple random sampling
12 out of 36 people are randomly selected
What is stratified sampling
Random samples from distinct groups
Geography
Sex
3 from each stratum are randomly selected process is random
What is cluster sampling
There are natural clusters rather than individual units and observations are made on all units within a cluster
more convient
1) Four out of the 10 clusters are randomly selected
2) All within the selected cluster are recruited
What is Multistage sampling
Primary sampling units are selected
Secondary units selected within primary units
Five out of the 10 clusters are randomly selected
Within the selected clusters participated are again randomly sampled
What is convenience sample
Selection from a non probability based source population due to ease of access to those individuals schools workplace organization or communities different than cluster because it involves randoming
What is purposive sampling
recruitment of the participants for a qualitative study based on the special insights they can provide
What is key informants
Individuals selected to participate in a qualittive study because they have expertise relevant to the study question
What is berksons bias
Can occur when cases and controls for a study are recruited from hospitals and therefore are more likely than the general population to have comorbid conditions sampling problem
What is healthy worker bias
When partcipants are recruited from occupational populations and therefore are systematically healthier than the general population
What is exclusion bias
Occurs when different eligibility criteria are applied to cases and contorls such as when controls with health conditions related to an exposure are excluded but cases with those comobidilites are not exlcuded