Using the Scientific Method and Appropriate Measurements

The Scientific Method•Question•Hypothesis•Testing Method•Conclusion

Law Theory

Using the Scientific Method and Appropriate Measurements

(continued)

• Appropriate Measurements– Reliability

• Interrater Reliability• Test-retest Reliability

– Validity• Internal Validity• External Validity

Objective Measurement• The scientific method assumes objective

measurement Bias Operational Definitions

• Objectivity can be achieved by– Observable behaviors– Precise Definitions– Quantitative Approach

Types of Research Descriptive research Correlational research Experimental research

Gathering Data About Children

Interviews•Children answer questions

Structured InterviewClinical Interview Naturalistic Observation

•Children are observed in everydaysettings

Structured Observation•Children do predetermined tasksin a laboratory

Correlation and Causation

•Correlational designs examine the relationship between two variables

•The relationship between two variables is known as their correlation

•The correlation coefficient is the statistic used to measure the direction and strength of correlation

•Correlation does not equal causationDirection-of-causation problemThird-variable problem

Five correlations

(a) The strongest possible positive correlation; without exception, the higher the value of one variable, the higher the value of the other. (b) A strong but imperfect positive correlation; a higher value of one variable tends to go with a higher value of the other. (c) The strongest possible negative correlation; the higher the value of one variable, the lower the value of the other.

Five correlations (cont.)

(d) A strong but imperfect negative correlation. (e) A total lack of correlation; any value of one variable is equally likely to be accompanied by any value of the other.

Scatter Plots

Correlation Example

• A high positive r (0.78) does NOT imply that reading is improved by watching Sesame Street

• Suggests the need for an experiment

Experimental Designs•Experimental designs are used to make cause–effect conclusions (causality)

Random assignmentExperimental control

Experimental and Control GroupsIndependent and Dependent Variables

© 1999 John Wiley and Sons, Inc.

An Example of a Group Study• Hypothesis: Watching Sesame

Street improves reading ability

• IV: Hours of watching

• DV: Reading level test scores

• Four groups are asked to watch either 2, 4, 8 or 10 hours per week

• Results: Increases in viewing time lead to increases in reading level

Other Experimental Designs• Sometimes a group is not available for a

study Study can be conducted using one subject Reversal Replication Design

© 1999 John Wiley and Sons, Inc.

Reversal-Replication Design

Designs for Examining Development

• Cross-Sectional

• Cross-Sequential

• Longitudinal

• Case Studies

• Cross-Cultural

• Comparative

Ethical Concerns• Research studies must be conducted to avoid

– Physical or psychological injury– Violations of privacy

• Subjects are ensured of Informed consent Anonymity and confidentiality Non-harmful procedures Justification of deception

Ethical Issues in Child-Development Research(Society for Research in Child Development’s Ethical Code)

Principle 1. NON-HARMFUL PROCEDURESPrinciple 2. INFORMED CONSENTPrinciple 3. PARENTAL CONSENTPrinciple 4. ADDITIONAL CONSENTPrinciple 5. INCENTIVESPrinciple 6. DECEPTIONPrinciple 7. ANONYMITYPrinciple 8. MUTUAL RESPONSIBILITIESPrinciple 9. JEOPARDYPrinciple 10. UNFORESEEN CONSEQUENCESPrinciple 11. CONFIDENTIALITYPrinciple 12. INFORMING PARTICIPANTSPrinciple 13. REPORTING RESULTSPrinciple 14. IMPLICATIONS OF FINDINGSPrinciple 15. SCIENTIFIC MISCONDUCTPrinciple 16. PERSONAL MISCONDUCT