Statistical Significance Vs Practical Significance Quick Quiz What

Quick Quiz What does the “p” in p-value stand for? What is another name

Statistical Significance is a mathematical judgment based on probability. “If p is low, the

Practical Significance Based on “effect size” or magnitude of differences/relationship; NOT on p-value. For

Useful Results Alternatively, a study may not reach statistical significance because it was based

Research is a judgment call! There are rarely any “hard and true numbers” to

Group Work Determine the following: 1. How useful is your research question? What are

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Statistical Significance Vs. Practical Significance

Quick Quiz What does the “p” in p-value stand for? What is another name for p-value? If p <. 05 then we say the results are …. ? When p is low then it is unlikely that the results we found were due to ______ alone.

Statistical Significance is a mathematical judgment based on probability. “If p is low, the null must go” It is heavily influenced by sample size Big sample = statistical significance

Practical Significance Based on “effect size” or magnitude of differences/relationship; NOT on p-value. For example, if you found in a sample of 1000 men and women that the average math score was Men (M = 103, SD = 8) Women (M = 101, SD = 6) This might reach the level of statistical significance, but has little practical value in the real world.

Useful Results Alternatively, a study may not reach statistical significance because it was based on a small sample, but the results point to differences that can be useful to someone trying to decide between two alternatives. Again, if p is low (e. g. , . 08), then the results may still be useful especially in small samples.

Research is a judgment call! There are rarely any “hard and true numbers” to answer your research questions. Research is a tool to answer useful questions We use judgment when we: Evaluate the usefulness of a research question Evaluate the methods used to answer it. Evaluate the accuracy of our findings. Evaluate the application of our findings.

Group Work Determine the following: 1. How useful is your research question? What are some practical applications of this research topic whether your study is statistically significant or not? 2. How effective is your plan for answering the research question? 3. How can you improve upon the method to increase your chances of being accurate in your conclusions? (Discuss Type II errors, sampling error, good IVs/DVs. ) 4. Regarding your DV, how “large” an effect would YOU need to see to be convinced that the IV worked? (regardless of p-value)