Inferential statistics

• Inferential statistics


  ways of analysing data using statistical tests that allow the researcher to make conclusions about whether a hypothesis was supported by the results.

  they assess whether the results are statistically 'significant
• The sign test (s)


  An inferential stats test that calculates the direction of differences between pairs of scores.
• When to use the sign test


  1.When looking for a difference

  2.When a repeated measures design (related data) have been used

  3.The data is organised into categories (nominal data)
• How to calculate the sign test


  1. Calculate the difference between each participant's scores (ignore any scores that do not show a difference)2. Use a plus or minus sign to indicate the direction of difference.3.The number of times the least frequent sign occurs is the S value.
• Observed/calculated value


  The value from the stats test.
• Critical/table value


  The value you look up in the table.
• N value


  The number of participants (minus those with tied scores)
• How to find the critical value


  Need to know the following:

  1. The level of significance (probability level)

  2. The number of participants (minus those with tied scores)

  3. Whether the hypothesis is one-tailed (directional) or two-tailed (non-directional)
• p=0.05


  the accepted level of probability/level of significance in psychology.
• p=0.01


  a stricter level of significance used when psychologists are conducting socially sensitive research
• p≤0.05


  the probability that the results occurred by chance is equal to or less than 5%
• p≥0.05


  the probability that the results occurred by chance is equal to or more than 5%