STATS TEST

• Reason for SD

  • determines wether groups of data are significantly different from each othrr
• when to choose SD?


  When looking at a spread of data around the mean
• Why choose spearmans rank correlation?

  Looking for associations between measurements from the same sample
• When to use chi squared?


  when looking at frequencies eg. finding number of individuals in particular categories
• NULL HYPOTHESIS FOR CHI SQUARED

  no significant difference between observed and expected result
• when to use T test

  Looking for difference between 2 means
• NULL HYPOTHESIS FOR T TEST

  There is no difference between x and y
• NULL HYPOTHESIS FOR SPEARMANS RANK

  There is no association between .... and .... (the measurements)
• SD

  • Overlap= groups of data not different from each other and are due to chance
  • No overlap= groups data different and not due to chshance
  • To test significance do a stats test
• Interpreting spearmans rank

  • if calc value of r is greater than critical value them reject null hypothesis as there is significant correlation btw 2 measurements
  • Probability less than 0.05% that differences are due to chance