Selection of Inferential Statistics

Cards (9)

  • Levels of measurement= the type of data we correct in the study (the dependent variable).
  • Nominal Data:
    • Is in categories- means it can only be measured by frequency
    • Cannot be ordered (it's either in the category or not- completed a marathon or didn't).
    • Use mode to calculate the measure of central tendency.
  • Ordinal Data:
    • Is ranked, you can count and order ordinal data, eg group of runners: 1st, 2nd, 3rd
    • Use median
  • Interval Data:
    • Has equal units of intervals throughout the scale
    • Usually on a standardised scale, eg time, temperature, weight, length etc
    • Example: the time in seconds racers finish the run
    • Use mean
  • Choosing the correct test:
    1. Is the study looking at a difference or a relationship? ie an experiment or a correlation.
    2. If it's a difference, then what is the experimental design? ie repeated measures or independent groups.
    3. What is the level of measurement produced? ie nominal, ordinal, interval.
  • Calculated value= the number you have calculated from your data set after using a statistical test.
  • Critical value= the number we compare our calculated value against to see if our results were significant (located in a table of critical values).
    • Level of significance (eg P<0.05)
    • One-tailed or two-tailed (hypothesis directional or non-directional)
    • Number of participants (N), maybe degrees of freedom too (N-1)
    • Our calculated value needs to be greater than or less than the critical value.
  • The Sign Test:
    1. One or two-tailed hypothesis & how many PPs were used.
    2. Work out of the change between each condition is positive or negative.
    3. Count up all the + & - (= values get left out which alters number of PPs).
    4. Take the total of the less frequent sign as your calculated s value.
    5. Compare calculated s value to the critical value & conclude (calculated value greater than/ less than critical value).