1. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Chapter 5 Selecting the Best Measure for Your Study

2. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Overview l Sensitivity l Scales of Measurement

3. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Sensitivity: Will measure be able to detect the differences you need to detect?

4. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Achieving the Necessary Level of Sensitivity l Look for High Validity l Look for High Reliability l Find Measures That Provide a Variety of Scores*

5. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Find measures that provide a variety of scores l Avoid Behaviors That are Resistant to Change l Avoid Measures That Produce a Limited Range of Scores l Ask How Much Instead of Whether l Add Scale Points to a Rating Scale l Pilot Test Your Measure

6. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Sensitivity: Conclusions l Scores must vary l But for the right reasons

7. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Scales of Measurement l What are the different scales of measurement? l What scale of measurement do you need? l What measure will provide that scale of measurement?

8. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley The Different Scales of Measurement l Nominal Numbers: Different Numbers Representing Different States l Ordinal Numbers: When Bigger Means More l Interval Scale Numbers: Knowing How Much More l Ratio Scales: Zeroing In On Perfection

9. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Why Measures Often Don’t Provide Ratio Scale Measurement l Often no absolute zero point l Even when there is an absolute zero point, changes in the measure do not perfectly correspond to changes in psychological reality.

10. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Which Level of Measurement Do You Need? l When You Need Ratio Scale Data l When You Need At Least Interval Scale Data l When Ordinal Data Are Sufficient l When You Only Need Nominal Data

11. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Ethical and Practical Considerations l Attempts to reduce subject biases may lead to ethical problems (spying, violating informed consent) l Desired measure may be too expensive or unavailable to you. l Practical concerns may lead you to choose a measure with high face validity

12. PowerPoint presentation to accompany Research Design Explained 5th edition ; ©2004 Mark Mitchell & Janina Jolley Concluding Remarks l The best measure for your study depends on validity and –Level of sensitivity you need –Scale of measurement you need –Ethical and practical constraints