Descriptive Statistics

• What are descriptive statistics used for?

  To analyze quantitative data
• What are the main components of descriptive statistics?

  • Measures of central tendency
  • Measures of dispersion
• What do measures of central tendency provide to researchers?

  • An average of the data set
• How many measures of central tendency are there?

  Three
• What are the three measures of central tendency?

  Mean, median, and mode
• How is the mean calculated?

  • Add all values in the data set
  • Divide the total by the number of values
• What is a strength of the mean?

  It is the most sensitive measure of central tendency
• What is a limitation of the mean?

  It can be easily distorted by extreme values
• What is the median?

  The middle value in an ordered data set
• How is the median determined if there is an even number of values?

  It is halfway between the two middle values
• What is a limitation of the median?

  It is less sensitive than the mean
• What is the mode?

  The value that is most common in a data set
• What is a unique characteristic of the mode in some data sets?

  There may be two modes (bi-modal)
• What is a limitation of the mode?

  It is not useful if all values in the data set are different
• What do measures of dispersion indicate to researchers?

  • How spread out the data set is
• How many measures of dispersion are there?

  Two
• What are the two measures of dispersion?

  Range and standard deviation
• How is the range calculated?

  • Difference between the highest and lowest value
  • Calculated by taking the lowest value from the highest value
• What is a strength of the range?

  It is easy to calculate
• What is a limitation of the range?

  It can be distorted by extreme values
• What does the standard deviation indicate?

  • The spread of data around the mean
  • The average distance from the mean
• What does a low standard deviation indicate?

  That the data is close to the mean
• What does a high standard deviation indicate?

  That the data is spread out over a range of values
• What is a strength of the standard deviation?

  It is the most sensitive measure of dispersion
• What is a limitation of the standard deviation?

  It can be distorted by extreme values