Population Data
Complete set of all items that interest an investigator
-all potential buyers of a new product
- all registred voters in a city or country
Random Sampling
- Sample of n objects from a population
- each member is chosen strictly by chance
- each member is equally likely to be chosen
Systematic Sampling
- every j th item in a population N, divided by the desired sample n
- the first number j is randomly chosen
Parameter
A numerical measure that describes a specific characteristic of a whole population
Statistic
A numeral measure that describes a specific characteristic of a sample (Stichprobe)
Descriptive statistics
Focus on graphical and numerical procedures to summarize and process data
Inferential Statistics
Focus on using data to make predictions, forecasts etc.