The Sign Test

• To be able to use the sign test, what TWO values must you be able to work out?


  S value

  N value
• Why use a statistical test?


  It allows a psychologist to make a CONCLUSION with a LEVEL of STATISTICAL CONFIDENCE, rather than result/relationship being possibly DOWN TO CHANCE
• What probability level is generally chosen by Psychologists?


  0.05
• What does 0.05 probability show?


  Shows that the probability of a result not being by chance is AT LEAST 95%
• Step 1 of the sign test?

  Subtract pp results: CONTROL CONDITION- EXPERIMENTAL CONDITION

  • in a new column record the SIGN
  • positive value = +
  • negative value= -
  • if the same record a 0
• Step 2 of the sign test?


  Get the S VALUE :

  • count number of times the least frequent sign occurs
• Step 3 of the sign test?


  Get the N VALUE:

  • Count the TOTAL NUMBER OF + and - signs
  • DO NOT COUNT THE 0 here
• Step 4 of the sign test?


  Decide if the hypothesis is one or two tailed