Ohne Titel

Statistics

1. Definition: the science of collecting, describe, analyze and interpret data.

2. Descriptive Statistics

   • The collection, organization, overview and presentation of sample data.

3. Inferential Statistics

   • Obtaining inferences or conclusions.

4. Population

   • Totality of the elements or things under consideration.

5. Sample

   • The portion of the population that is selected for analysis.

6. Parameter

   • Measure of overview that is calculated to describe a characteristic of a population.

7. Random Variables

   • Qualitative "Categorical"
     • Nominal
       • Gender, religion or political affilation
     • Ordinal
       • Unique meaning
   • Quantitative "numerical"
     • Discrete
       • Process of counting
     • Continues
       • process of measurement
     • Interval
       • Fahrenheit
     • Ratio
       • Weight of an object. (they can´t have negative weight)

8. Sampling Methods

   • Population Parameter
   • Sample Statistics
   • Probability Samples Each population element has a known (non-zero) chance of being chosen for the sample.
     • Simple
       • Selected randomly
     • Systematic
       • Colors
     • Stratisfied
       • Divided
     • Cluster
       • Group selected randomly
     • Voluntary
       • Group selected for specific characteristics
     • Convenience
       • Persons with selected characteristics
   • Non-Probability samples We don´t know the probability that each population element will be chosen.
     • Voluntary sample
       • People who self-selected into the survey
     • Convenience sample
       • People who are easy to reach.

9. Visual Displays of data

   • Line Graphs
   • Circle Graphs
   • Bar Graphs
   • Steam and Leaf
   • Histogram

10. Measures of central tendency

    • Mean X=∑x/n
    • Weighted mean= ∑〖(x*f)〗/∑f
    • Mode--> value that occurs often
    • Median n+1/2

11. Measures of Dispesions

    • Standard Deviation √(∑〖(x-X) 2 〗)/n-1
    • Range "greatest value- the least value
    • Chevyshev´s teorem
      • 1-1/k^2
    • Coefficient of Variation
      • Population v=α/μ
      • Sample v= SI/X

12. Measures of Position

    • Decile (10)
    • Quartile(4)
    • Percentile (1% too 100%)