Inferential statistics

• What are probability values?

  Probability is the likelihood that results are due to a real correlation which you are testing. This is also known as the level of confidence in the significance of the results.
• What is the standard probability value in psychology?

  95%
• What are significance levels?

  When psychologists carry out investigations they want to be sure that their results are not due to chance factors. A statistically significant result is one that is unlikely to have occurred by chance.
• What is the standard significance level in psychology?

  0.05
• What are observed/calculated values?

  The numerical value that is created as a result of an inferential statistical analysis of data. (the results of a statistics test)
• What are critical values?

  Values taken from a pre-calculated table for each stats test. They are compared with the observed/calculated value to determine whether the experimental hypothesis can be rejected or accepted.
• What is the 'R up' rule?

  If there is an R in the shortened name of the stats test, then the observed/calculated value needs to be equal to or higher than the critical value for the results to be considered statistically significant. If there is not an R in the shortened name of the stats test then the rule is reversed.
• What type of study is each stats test?

  Chi-squared: difference

  Mann-Whitney U: difference

  Sign Test: difference

  Wilcoxen T: difference

  Spearman's rank: correlation
• What level of measurement does each stats test use?

  Chi-squared: nominal

  Mann-Whitney U: ordinal, interval, ratio

  Sign Test: nominal

  Wilcoxen T: ordinal, interval, ratio

  Spearman's rank: ordinal, interval, ratio
• What design does each stats test use?

  Chi-squared: independent measures

  Mann-Whitney U: independent measures

  Sign Test: repeated measures, matched pairs

  Wilcoxen T: repeated measures, matched pairs

  Spearman's rank: related data