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 MedianMeanMost 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