Descriptive Statistics

• What are types of descriptive statistics?

  Measures of central tendency

  Measures of dispersion
• What are the levels of measurement?

  Nominal data (Data in separate categories)

  Ordinal data (Data in order but not set intervals)

  Interval data (Data measured in units of equal intervals)
• What are the measures of central tendency?

  Mean 

  Median

  Mode
• When to use the mean?


  For interval data
• When to use median?


  Interval/ordinal data
• When to use mode?

  Any level of measurement
• How do you calculate the range in Psychology and why?

  Minus the lowest value from the highest value adding 1. This is done to eliminate margin of error
• What is standard deviation?

  It is a measure of dispersion

  A low SD means the data is closer to the mean (results are consistent)

  A larger SD means the data is spread out around the mean (results are inconsistent)
• What % fall between 1,2,3 SD within the mean?

  1 SD = 68%

  2 SD = 95%

  3 SD = 99.7%
• What is the order of measures of central tendency on a positive skew?

  Mode 

  Median

  Mean

  Most of the distribution is on the left
• What is the order of measures of central tendency on a negative skew?

  Mean

  Median

  Mode

  Most the distribution is on the right