Statistics

Statistics

1. Types of variables

   • Qualitative: Not countable
   • Quantitative: Countable

2. Measurement scales

   • Nominal
     • Identity
   • Ordinal
     • Identity and magnitude
   • Interval
     • Identity, Magnitude and equal intervals
   • Ratio
     • Identity, magnitude, equal intervals and minimum value of 0

3. Sampling methods

   • Simple
     • Stratified sampling
       • Strata: Groups divided by characteristics
     • Cluster sampling
       • Random groups of the population
     • Systematic sampling
       • Has an specific process
     • Multistage sampling
       • Use of various methods
   • Probability
   • Non-probability
     • Quota
     • Voluntary sample
     • Convinience sample

4. Visual displays of data

   • Based on frequency
     • # of times an event occurs
     • Histogram
     • Bar graphs
     • Linear graphs
     • Circe
     • Steam and Leaf

5. Measures of central tendency

   • Mean: Known as the average
   • Mode: The most repeated value
   • Median: Middle event located in the list

6. Measures of dispersion

   • Standard deviation
     • Square root: x-x´/n-1
   • Range
     • Value between the biggest and smallest value
   • Coefficient of variation
     • S/X´
   • Chevyshev´s Theorem
     • 1-1/K^2

7. Measures of position

   • Percentiles
     • 0%-100%
   • Decile
     • D1-10
   • Quartile
     • Q1-4
   • Box plot
     • It´s a graph
   • z score
     • X-X / S