stats tests

• test of difference 


  • used for experiments to compare two conditions and see if there is a difference between them. Related data is when the two sets of data are from the same participants (repeated measures or matched pairs), and unrelated data is from two different sets of participants (independent measures).
• chi squared 


  • test of difference
  • nominal data
  • independent groups

  Calculating degrees of freedom (df)= (r-1) x (c-1)

  r= number of rows, and c= number of columns
• sign test


  • test of difference
  • nominal data
  • repeated measures
• spearman's rho


  • test of correlation/relationship
  • ordinal data
  • repeated measures
• Pearson's R 


  • correlational
  • interval data
  • repeated measures
• wilcoxon's 


  • test of difference
  • ordinal data
  • repeated measures
• Mann Whitney U


  • test of difference
  • interval data
  • independent groups
• Unrelated T test


  • test of difference
  • interval data
  • independent groups
• Related T test 


  • test of difference
  • interval data
  • Repeated measures
• sign test 


   statistical test used to analyse the direction of differences of scores between the same or matched pairs of subjects under two experimental conditions

  • We use this test when differences predicted between two sets of related data (such as in an experiment).  N= number of participants, S= the observed value
• how to do sign test 


  1. Subtract each value in the control from the experimental condition, recording (+ or -) 
  2. Count number of times less frequent sign appears: S
  3. Count the total number of pluses and minuses : N
  4. Use table of critical values, picking one or two tailed as appropriate. The critical value between N and the 0.05 level of significance. S must be less than or equal to the critical value to be significant
  5. State the conclusion (i.e: as the result is significant/not significant we cannot accept the null/alternative hypothesis, therefore we accept the alternative/null hypothesis)
• parametric test

  1. Data must be interval level-
  2. The data drawn from a population which would be expected to show normal distribution for variable being measured. Variables that would produce skewed distribution not appropriate for parametric tests.
  3. the set of scores in each condition should have similar dispersion or spread. way of determining variance is by comparing the standard deviations in each condition; if similar, a parametric test may be used. In a related design assumed two groups scores have similar spread.