Descriptive statistics

• Define 'measures of central tendency'

  The general term for any measure of the average value in a set of data
• Define 'mean'

  The arithmetic average calculated by adding up all the values in a set of data and dividing by the number of values
• Evaluate 'mean'

  Strengths: representative

  Weaknesses: easily distorted by extremes
• Define 'median'

  The central value in a set of data where the values are arranged from lowest to highest
• Evaluate 'median'

  Strengths: not affected by extremes

  Weaknesses: not representative
• Define 'mode'

  The most frequently occuring value in a set of data
• Evaluate 'mode'

  Strengths: easy to calculate

  Weaknesses: can be several modes in one data set
• Define 'measures of dispersion'

  The general term for any measure of the spread or variation in a set of scores
• Define 'range'

  A simple calculation of the dispersion in a set of scores which is worked out by subtracting the lowest score from the highest score
• Evaluate 'range'

  Strengths: easy to calculate

  Weaknesses: not representative
• Define 'standard deviation'

  A sophisticated measure of dispersion in a set of scores that tells us by how much on average each score deviates from the means
• Evaluate 'standard deviation'

  Strengths: precise measure

  Weaknesses: distorted by extremes