The process of statistical study
For systematic sample
K=population/sample; K means every nth
Case control
retrospective. Looks at "old" data
A school administrator chooses one person at random from each class.
stratified
A scientist chooses twenty people at random from each neighborhood.
stratified
A statistics student chooses twenty people at random from each zoning district.
stratified
First, the population is subdivided by class. Then a college student uses a random number generator to select fifty members from each class to study.
stratified
A scientist chooses twenty people at random from each math class.
systematic
stratified sample/ quota sampling
when members of the population are divided into two or more subgroups
When many participants in a study have strong opinions, could occur.
participation Bias
procedure
1) Determine the design study (a. state the question b. det. population and variables c. det. method of sampling 2) Collect 3) Organize it 4)Analyze
Metal-Analysis
Compiles info from varies/ other studies
First, the population is subdivided by city. Then a crime researcher uses a random number generator to select fifteen members from each city to study.
Stratified
random sample
all MEMBERS of a population have an equal chance of being chosen; out of a hat
Simple random sample
all SAMPLES from a population have an equal chance of being chosen
Cluster Sampling
also divided into groups but the sample consists of the data collected from every member of only those clusters that are randomly selected or chosen.
systematic sampling
by selecting every nth member of the population
For budget purposes, a college president needs to know the average salary of instructors at their university.
census
For tax purposes, a college president needs to know the average cost of health plans of employees at their business.
census
A market researcher interviews each member from each of the five randomly chosen freshmen dormitories at universities across the country.
cluster
A random number generator is used to choose twenty-five zip codes. Then a biologist collects data from each person in these zip codes.
cluster
A statistics student interviews each member from each of the ten randomly chosen neighborhoods throughout a city.
cluster
convenience Sampling
convenient for the researcher to select.; prone to creating nonrepresentative samples
A market researcher interviews the first ten students to arrive.
convinient
longitudinal study
follows a group over a period of time. prospective in time
The process of statistical study
gathering, organizing and analyzing
representative sample
has relevant characteristics as the population and does not favor one group from the population over another.
experiment
identify cause-effect relationships between variables
Case study
looks at multiple variables that affect the result
observational studies
observing data that already exists; cannot determine cause-effect relationship of variables
