Statistics

Statistics

1. Basic Concepts

   • Population: total of elements in consideration.
   • Sample:portion of the population selected for analysis
   • Parameter:measure tha describe a characteristic of the population.
   • Statistic: measure that describe a characteristic of a simple simple of the population.
   • Random Vatiables
     • Qualitative: categorical responses.
     • Quantitative: numerical answers

2. Visual displays of data

   • Displays
     • Line Graphs
     • Circle Graphs
     • Bar Graphs
     • Steam and Leaf
     • Histogram
   • Frecuency distribution
     • Relative frecuency
       • Porcentaje
     • Frecuency
       • Number of times the corresponding ítem ocurred in the data set.

3. Measure of central tendency

   • Mode
     • Value that occures more often.
   • Mean
   • Median

4. Measurement Scales

   • Nominal
     • Identity
       • Values represent a descriptive category (gender)
   • Ordinal
     • Identity, Magnitude
       • Each value has a unique meaning and has an ordered relationship.
   • Interval
     • Identity, Magnitude, equal intervals
       • Can have values less tan 0
   • Ratio
     • Identity, Magnitude, equal intervals, value of zero
       • Each value has a unique meaning

5. Sampling Methods

   • The way that observations are selected from a populations
   • Population parameter:true value of a population attibute
   • Sample statistics: is an stimulate based on simple data of a population parameter.
   • Probability Samples
     • Simple random Sampling
       • Stratified Sampling(divid in different groups)
         • Cluster sampling(divide in sections)
           • Multistage sampling
             • Systematic random Sampling (choose every 4, 5, 6...elements)
   • Non-probability samples
     • Voluntary sample (specific group)
       • Convenience Sample (preguntas a cualquiera)

6. Measure of position

   • The z-score
   • Percentile
   • Box Plot
   • Finding quartiles

7. Measure of dispersions

   • Range: greatest value-least value
   • chevyshev´s theorem
   • Coefficient of variation
   • Standard deviation

8. Science of collecting, describe, analyze, and interpret data.

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