Test 3 Flashcards
(200 cards)
Population
Patients who share a similar characteristic, condition, disease, etc. of interest to researcher
Who is the population
Among women with breast cancer undergoing outpatient chemotherapy, how does receiving massage therapy in addition to usual care as compared to usual care only affect pain and fatigue?
POPULATION vs sample
complete set of persona or objects
Common characteristic
of interest to the researcher
population vs. SAMPLE
subset of a population
sample represents the population
Probability
- -uses random methods
- -Each element in the population has an equal, independent chance of of being selected
- -increased likelihood to yield representative sample
- -increased cost and complexity
types of probability
simple
stratified
systematic
cluster
Non-Probability
- -Random methods not used
- -Less likely to approximate target population
- -Creates a biased sample
- -increased convenience
- -decreased cost and complexity
types of Non-probability
convenience
quota
purposive
Probability sampling: simple
- -most basic form of probability
- -importance of this sampling strategy
- ——–Equal chance of selection
- ——–independent chance of selection
Advantages of SIMPLE
Little knowledge of population is needed
Most unbiased of probability method
Easy to analyze data and compute errors
Disadvantages of SIMPLE
Compete listing of population is necessary
Time consuming
Probability Sampling: STRATIFIED
- -type of probability sampling
- -population divided into subgroups or strata
- -Example of strata:
- ——gender
- ——age groups
- ——years of experience
- -Random sample taken from each strata
Proportional stratified sampling
sampling fraction for each stratum determined by proportion in total population
Disproportional stratified sampling
determine stratum is represented
used when strata are very unequal
Advantages Stratified
- -Increases probability of being representative
- -Ensures adequate number of cases for strata
Disadvantages of stratified
- -requires accurate knowledge of population
- -may be costly to prepare stratified lists
- -statistics are more complicated
Probability Sampling: Systematic
Selection of every kth case
—–selection interval determined by overall size of population divided by # needed for sample size
Example: Sample size of 100 needed from 1000 potential participants.
1000/100=10
So every 10th individual on the list is selected to create the sample of 100 people
Advantages of systematic
Easy to draw sample
Economical
Time-saving technique
Disadvantages of systematic
Samples may be biased
After first sample is chosen, no longer equal chance
Probability Sampling: Cluster
- -Larger groups or clusters, not people, are selected from population
- -Simple, stratified or systematic random sampling may be used during each phase of sampling
Advantages of Cluster
- -Saves time and money
- -Arrangements made with small number sampling units—-Characteristics of clusters or population can be estimated
Disadvantages of Clusters
- -Causes a larger sampling error
- -Requires each member assignment of population to cluster
- -Uses a more complicated statistic analysis
Nonprobability Sampling
- -Sample elements are chosen nonrandomly
- -Produces biased sample
- -Each element of the population may not be included in the sample
- -Restricts generalizations made about study findings
- -Common among nursing research studies
Advantages of nonprobability sampling
Costs less
Takes less time