Unit 13

• Alpha Level


  The threshold probability below which a test statistic is deemed to be unlikely to have originated from the sampling distribution

  • Probability values below are considered statistically significant
• Conclusion Validity


  The extent to which the conclusions about the relationships among variables, based on our analysis of the data, are correct
• Error Variance


  The variability of each score relative to its groups means.
• Inferential Statistics


  Estimates weather the results observed based on a sample data are generalizable to the population of the sample
• Null hypothesis


  States that there is no effect on the population and that any effect observed is due to random error and does not represent the population
• Power


  The probability of correctly rejecting the null hypothesis using a particular statistical test
• Probability


  The likelihood that a given event will occur
• Publication Bias


  The bias in the literature that emerges because statistically significant results are more likely to be published in scientific journals than non-significant results
• Research Hypothesis


  The statement that some phenomenon exists within a population

  • typically contrasts the null hypothesis
• Sampling Distribution


  A frequency distribution of values obtained if a study was repeated an infinite number of times, using the exact same parameters

  • Used to evaluate the likelihood of a given result based on chance alone
• Statistically Significant


  Observing that an outcome has low probability of occurrence, assuming the null hypothesis is correct
• Systematic Variance


  Variability in a set of sources that is the result of the independent variable; statistically, the variability of each group mean from the grand mean of all participants
• T-test


  Statistic used to determine if there is significant difference between the means of two groups
• Type One Error


  An incorrect decision to reject the null hypothesis, when it is in fact true
• Type Two Error


  An incorrect decision to accept the null hypothesis, when it is in fact false
• F Test 


  A test that companies the variances between two samples, or the ratio of variance between more than two samples.