4.1

• Descriptive Statistics


  Provides a summarized and organized characteristics and distribution of values in one or more datasets
• Data set


  A collection of responses or observations from a sample or entire population
• Types of Descriptive Statistics

  • Distribution
  • Central Tendency
  • Variability (Also Called Dispersion)
• Distribution


  • Datasets consist of a distribution of scores or values
  • Statisticians use graphs and tables to summarize the frequency of every possible value of a variable, rendered in percentages or numbers
  • Statisticians depict frequency distributions as either a graph or as a table
• Central Tendency


  Measures of central tendency estimate the center, or average, of a data set
• Measures of Central Tendency

  • Mean
  • Median
  • Mode
• Mean


  The most common method for finding averages, calculated by adding all the response values together and dividing the sum by the number of responses
• Mode


  The most frequent response value in a dataset
• Median


  The value in the precise center of the dataset when arranged in ascending order
• Variability (Also Called Dispersion)


  The measure of how spread out the responses are in a dataset
• Aspects of Variability


  • Range
  • Standard Deviation
  • Variance
• Range


  The difference between the highest and lowest values in a dataset
• Calculating Standard Deviation


  1. List the scores and their means

  2. Find the deviation by subtracting the mean from each score

  3. Square each deviation

  4. Total up all the squared deviations

  5. Divide the total by the number of scores

  6. Take the square root of the result