data analysis

• Graphs


  Types of graph
• Bar Charts


  • Uses bars to describe categorical data
  • As the data are discrete (not continuous) there are gaps between the bars
• Scatter diagrams and correlations

  • Only used for correlations
  • Shows a relationship between two variables
  • We add a line of best fit

  
• In psychology, data may be presented a number of ways but this will depend on type of data collected (quantitative or qualitative)

  
• You will not be required to carry out any calculations in the exam BUT you do need to be able to name, recognise, + in some cases draw + interpret data
• Measures of Central Tendency

  • Inform us about central (middle) values for a set a data
  • They are 'averages' + can be calculated in different ways

  
• Mode


  Most frequently occurring value
• Median


  Middle value when scores are arranged in descending order
• Mean


  Arithmetic average (add up all scores + divide by number of scores)
• The Mean


  • You experiment consists of 20 people standing on one leg for as long as they can, so you add up all their times + divide by 20 to get mean (mean length of time that people can stand on one leg for)
• The Median


  The middle value when all the scores are in order
• The Median


  • Easy to calculate with a small data set
  • Hard to calculate with a large data set
• The Mode


  The most frequently occurring score
• The Mode


  • Easy with a small data set
  • Doesn't take into account all data
• Measures of Spread/Dispersion


  Describe how dispersed or spread out data items are
• Range


  Difference between highest + lowest item in a set of data. Usually 1 is added to balance out bottom + top values.
• Standard deviation


  Shows amount of variation in a data set. It assesses spread of data/difference between data points + mean.

  
• Groups with scores that are more spread out have larger SDs, groups with closely clustered scores have smaller SDs
• The range


  Difference between highest + lowest value
• The range


  • Easy to calculate and quick
  • Impacted by extreme scores
• Normal Distributions


  • The mean, mode + median are in the centre
  • Has 50% of the scores to the left and 50% to the right
  • Symmetrical