Statistics

Statistics

1. Visual displays of data

   • Frecuency
     • # of times the item occurred in the data set.
   • Displays
     • Histogram
     • Steam and leaf
     • Bar Graph
     • Circle Graphs
     • Line Graphs

2. Science in charge of collect, analyze, present and interpret data.

3. Basic Concepts

   • Population
     • Total elements
   • Sample
     • Section of the population, selected for its analysis.
   • Variables
     • Quantitative
       • Discrete
         • By counting
       • Continuous.
         • By measuring
     • Qualitative
       • Categorical answers

4. Measurement scales

   • Nominal
     • Represent a descriptive category, has magnitude.
   • Ordinal
     • *Identity and magnitude *Unique meaning
   • Interval
     • Identity, magnitude, and equal intervals.
   • Ratio
     • Identity, magnitude, equal intervals, and a minimum value of zero.

5. Sampling Methods

   • Probability
     • Simple random
     • Systematic
     • Stratified
     • Cluster
     • Multistage
   • Non-Probability
     • Voluntary
     • Subjects self-selected
     • Interested in the survey's topic
     • Convenience Sample
       • Subjects easy to reach.

6. Measures of central tendency

   • Mean
     • Mean=∑x/n
   • Mode
     • The one that occurs more often.
   • Median
     • Medium value (ordered data)

7. Measures of Dispersion

   • Range
     • Greatest value- least value
   • Standard Deviation
     • σ=√ (x-mean)^2 / n-1
   • Chevyshev's Theorem
     • 1-1/k^2

8. Measures of position.

   • Box plots
   • z-score
     • X-mean/std. deviation
   • Decile and Percentile
   • Quartiles
     • Q1= 25% Q2= 50%=median Q3=75%