Chapter 5 Selecting Participants Flashcards
Target population
Group defined by researchers interest
More specific
Population
Entire set of individuals of interest to a researcher
Accessible population
Subset of target population which is LOCALLY AVAILABLE for study
Sample
Set of individuals selected from population who actually participate in the study
Representative sample
A sample with same characteristics as population
Biased sample
Differ from those of population
Selection or sampling bias
Occurs when participants or subjects are selected in a manner that increases the probability of obtaining a biased sample.
Law of large numbers
Larger than sample size. More likely to be accurate
Probability sampling
Better samples
Harder, less practical, more timing
Simple random sampling steps
Clearly define population
List all members of population
Use random process to select individuals from list
Systematic sampling
Easier to conduct, high degree or representativeness
Every nth person of study; identify all
Stratified sampling
Divide population into segments or strata that are important to your measurements, randomly draw individual from each
Proportionate stratified random sampling
Break population into strata and then make sure proportions of subgroups in populations are matched in sample
Ensures more representative sample
Cluster sampling
Used when population are too large to allow cost effective simple sequential sampling or when population are already naturally grouped into small units.
Snowball sampling
Asking members of the sample to identify additional members of population who could participate in research
