Section 4 R Atomic Class

4.1 Types of Study

Retrospective study

Observational study

Designed experiment

4.2 Types of Variables

  • Quantitative

  • Qualitative

4.3 Quantitative (Numerical)

  • Continuous
    • continuum of values
    • Example: temperature, height, weight, body mass index
  • Discreet
    • integer values - finite
    • Example: number of patients, number of children

4.4 Qualitative (Categorical)

  • Nominal
    • Categories that cannot be ranked – two or more levels
    • Example: eye colour, gender, identification number, sample number
  • Ordinal
    • Categories with possible natural order/ranking
    • Can assign number but no numerical meaning of differences
    • Example: grades, satisfaction level