Descriptive statistics

• Range


  Represents spread

  Tells us whether a set of data are close together or spread out

  Subtract the lowest value from the highest value
• Range Evaluation


  +Easy to calculate

  -Distorted by extreme score
• Mean


  Add up all the scores in a data set and divide by number if scores there are
• Mean Evaluation


  +Uses all data values, most sensitive measure

  -Distorted by extreme values
• Median


  The middle value in a set if data
• Median Evaluation


  +Not affected by extreme values

  -Doesn't take all of the data into account
• Mode


  The most common score in a set of data
• Mode Evaluation 


  +Very easy to calculate

  -Quite unrepresentative
• Scatter diagrams


  To display correlation

  Each co-variable on each axis
• Frequency tables


  A systematic way of representing data, organised in rows and columns

  Displays how often an event ocurred
• Histogram

  Continuous data

  No space between bars
• Bar chart


  Discrete data

  Bars not touching
• Normal distribution


  Symmetrical spread of frequency data that forms a bell shaped curve

  Mean=Median=Mode