Vocab ch.1-2 Flashcards
Population
Who or what we want to understand
Sample
A subset of the population (representative)
Statistic
Anything we can calculate from a sample or a characteristic of a sample
Parameter
Anything we would calculate from a population (if we could see it all)
Variable
A characteristic that varies (potentially) from person to person (or object to object) in the population. Noted as X, Y
Data
Any observed value of a variable that we record, noted in lower case x,y
Descriptive statistics
Method for organizing and summarizing data
Inference Statistics
The use of sample to draw conclusions about populations, also methods for measuring the reliability of those conclusions
Qualitative (Categorical)
An attribute who’s value is indicated by a label
Quantitative (Numerical)
Discrete- We count; we record a number for which you can list all of the possible values
Continuous- We measure; we record a number after rounding
Another word for “groups”?
Strata
Simple Random Sample SRS
Each possible sample of the same size is equally likely to be the one chosen. Representative sample, non-representative (biased)
- Sampling with replacement
- Sampling without replacement
- Random-number generators
Stratified Sample
- Divide pop into groups called strata
2. Take a proportionate sample random sample from each stratum to make a sample
Cluster Sample
- Divide pop into groups (clusters)
- Randomly select some clusters
- From each cluster include all members in sample
Systematic Sample
- Number elements of pop from 1 to N
- Randomly choose starting point k and in increment m
- Then take sample = (k,k+m,k+2m,….)
