the sign test

• What is the Sign Test used for?


  To determine if results are significant
• What are the levels of measurement in statistics?


  • Nominal: Data separated into categories (e.g., football teams).
  • Ordinal: Ordered numerical data that is subjective (e.g., questionnaire ratings).
  • Interval/Ratio: Ordered numerical data in objective units (e.g., temperature, length).
• What is nominal data?


  Data separated into categories
• Give an example of nominal data.


  Football teams: Arsenal, Chelsea, Crystal Palace, Millwall
• What is ordinal data?


  Numerical data that is ordered but subjective
• How is ordinal data measured?


  Using a scale where the difference between items need not be the same
• What is an example of ordinal data?


  Questionnaire ratings from 1 (very strongly agree) to 5 (very strongly disagree)
• What defines interval/ratio data?


  Numerical data that is ordered and in objective units
• What is an example of interval data?


  Temperature
• What is an example of ratio data?


  Length
• Why do we conduct statistical tests?


  To determine if results are significant or due to chance
• What do measures of central tendency and dispersion tell us?


  They cannot tell us about significance
• How do we know if results are significant?


  If they haven't occurred through chance
• What is the level of significance commonly used in statistics?


  5% or p=0.05
• When should the Sign Test be used?


  • Level of measurement is nominal (categorical).
  • Looking for a difference between conditions (not correlation).
  • Experimental design is related (matched pairs or repeated measures).
• What is the first step in conducting a Sign Test?


  Work out the 'sign' (+ or -)
• How do you calculate the value of 'S' in the Sign Test?


  Find the lowest score excluding any nil scores
• What does 'N' represent in the Sign Test?


  The total number of scores, excluding nil scores
• What is the purpose of finding the critical S value?


  To compare with the calculated value to determine significance
• How do you determine if your results are significant in the Sign Test?


  If the calculated value is less than or equal to the critical value