(9) Sampling Design
The Nature of Sampling
key terminology
Element
used to find data to form an analysis
Population
group that is under investigation
Sampling Units
nonoverlapping elements from a population
Sampling Frame
physical representation of all elements
Sample
a group from the population that is under investigation
Parameter/Statistic
summary descriptors of a given variable in the population/ " in the sample
Sampling Errors
errors in the study
Statistical and Sample Efficiency
Sampling Plan
formal specification(plan)
rationale
resource constraints
accuracy
destructive measurement
the sampling process
Step 1: Select the population
Step 2: Select sampling units
Step 3: Select a sampling frame
Step 4: Select a sample design
Step 5: Select size of sample
Step 6: Select a sampling plan
Step 7: Select the sample
The Feel Good Store (Project)
Sampling is important to our project because:
It can help to provide a number of conclusions in our study
can help find a less bias response, using the appropriate design
Some major considerations when choosing our design:
cost
time
An Introduction to the Philosophy of Sampling
goals
1. to acqaint you with the underlying philosophy of sampling
2. to show how and why samples can be used to estimate the parameters of a population of interest
probablity designs/ nonprobablility designs
Practical Considerations in Sampling
incidence and response rates
Incidence
% of the pop. that possesses the trait to be included in the study
Response rate
% of respondants contacted who participated
internationalization of the marketplace
Sample Designs
Probability designs
Simple Random
assign a number to each subject; select sample using the numbers
Systematic
natural ordering or order population
Multistage Random
use random ampling in each sampling stage where there are 2 stages
Stratified
a sample is selected from each stratum(non-overlapping groups)
Cluster
seperated into groups by proximity
Stratified Cluster
combo. of stratified and cluster
Repetitive
combining two or more of the designs above
Nonprobability designs
Judgment
selected by the researcher to rep. the population of interest
Convenience
convenience of the researcher is important
Snowball
samples are referred by the chosen population