Data Collection and Experimental
Design
Data Collection Methods
 1. Observational study
 2. Experiment
 3. Simulation
 4. Survey
EX: which method of data collection
would you use? Why?
 A study of the effect of a product’s warning label
to determine whether consumers will still buy the
product.
 A study of how often people wash their hands in
public restrooms.
Sampling Techniques
 Census: a count or measure of the entire
population. SAMPLES are part of the population.
 Random Sample: every member of the
population has an equal chance of being selected.
 Stratified Sample: the population is divided into
subsets (strata), then a sample is randomly
selected from each of the strata.
More Sampling Techniques
 Cluster Sample: population is divided into groups
(clusters), then select all members in one or more
clusters.
 Systematic Sample: Each member of the
population is assigned a number, placed in order,
then select every nth member starting at a
randomly selected number.
 Convenience Sample: uses only available
members of the population.
EX: What sampling technique
was used?
 Chosen at random, 500 rural and 500 urban
persons age 65 and older are asked about their
health and their experience with prescription
drugs.
 From calls made with randomly generated
telephone numbers, 1012 respondents are asked if
they rent of own their residences.