1. Sources of bias in research Your bait of falsehood takes this carp of truth; And thus do we of wisdom and of reach, With windlasses and with assays of bias, By indirections find directions out. -Wm. Shakespeare (“Hamlet”)

2. Scientists’ attitudes There is always a degree of uncertainty; Important to remain open-minded; Everyone is fallible; Must be skeptical; Must be cautious; Must be ethical.

3. Common sources of bias Adjustment and narrowing Availability Selective perception Wishful thinking Base rate Cognitive conservatism Order effects

4. More sources of bias… Data saturation Law of small numbers Representativeness Desire for self-fulfilling prophecies Fact-value confusion Attribution errors Gambler’s fallacy

5. Even more sources of bias… Overconfidence Redundancy Motivational biases –Fear –Dishonesty –Greed

6. Avoiding bias Recognize that biases exist Sample information broadly Look for data on both sides Use models and consistency analysis Use proper scaling methods Give equal treatment to qualitative and quantitative data

7. Avoiding bias (cont’d)… Ensure that sample characteristics are associated and presented with the data Analyze past decisions Determine prior good and poor decisions Present information/data in several forms

8. Selection bias… can occur in group comparison studies and retrospective studies

9. Observer bias… Can occur in behavior observation research

10. Recall bias… Can occur in survey research -social desirability effects

11. Non-response bias… Can occur in survey research

12. Research designs How was the sample selected? Is the sample representative of population? What type of study –Descriptive? –Correlation? –Group comparison? –Qualitative or historical? What is known about the measures? Data analyses appropriate?

13. Interpreting Research Results Are conclusions consistent with results? Practical vs. statistical significance? Can cause and effect be established? Importance of results for the population?