types of data

• a limitation of primary data is that it is time consuming and expensive to collect and analyse
• ordinal and interval data can be put in order
• nominal data is categorical, not ordered or quantitative
• Tests of difference

  • Unrelated Design (independent groups)
  • Related Design (Repeated measures)
• Tests of association or correlation

  • Nominal Data
  • Ordinal Data
  • Interval Data
• Nominal Data

  • Chi-squared
  • Sign test
• Ordinal Data

  • Mann-Whitney
  • Wilcoxon
  • Spearman's Rho
• Interval Data

  • Unrelated t-test
  • Related t-test
  • Pearson's r
• limitation of range

  • only takes into account the 2 most extreme values
  • unrepresentative of the data as a whole
  • does not give a fair representation of the general distribution of the score
  • e.g. influenced by outliers