1. Types of Psychological Research

2. 193050607080 194040506070 195030405060 196020304050 1980199020002010 Time of Measurement Cohort

3. 193050607080 194040506070 195030405060 196020304050 1980199020002010 1 Column = Cross-Sectional Study Controlled = Time of Measurement Confounded/Extraneous = Age & Cohort Advantages Cost Effective Easy to Manage/Time Effective Disadvantages Cannot Assess Individual Development Nothing Learned about Continuity of Dev. Cohort Effects*** (Grand Assumption)

4. 193050607080 194040506070 195030405060 196020304050 1980199020002010 1 Row = Longitudinal Study Controlled = Cohort Confounded/Extraneous = Age & Time of Measure Advantages Same Individuals/Individual Development Only Way to Answer “Stability/Instability” Disadvantages Costly Time Consuming/Labor Intensive Difficulty in Maintaining Contact Focus of Theory/Research May Change Drop-Outs/Deaths (Including Researcher) Selective Attrition/Non-Rep. Sample (Bias) Practice Effects/Test Familiarity Cross-Generational Problem

5. Cross-Sectional Question: Do 70-year-olds hold more conservative gender-role attitudes than 30-year-olds because they are older or because they are members of a different cohort raised in a more traditional period? Longitudinal Question: Are there responses in 2000 more liberal than 1960 because gender-role attitudes become more liberal with age or because major societal changes occurred from one time of measurement to the next? Cross-Sectional Question: When giving intelligence tests to representative samples of people, researchers consistently find that older adults give fewer correct answers than do younger adults. Why is this? Is it there age, or there cohort? Longitudinal Question: When the same people are retested over a series of years, intelligence remains stable, until late in life. Is the stability of intelligence attributable to age or societal advances at the time of measurement?

6. The Best of Both Worlds They can tell researchers: Which age-related trends are truly developmental in nature and reflect how most people, regardless of cohort, can be expected to change over time (age effects). Which age-trends differ from cohort to cohort and suggest that each generation is affected by its distinct growing-up experiences (cohort effects). Which trends suggest that events during a specific period similarly affect all cohorts alive at the time (time of measurement effects). Sequential Designs Untangle the Effects of Age, Cohort, & Time of Measurement & Indicate Which Age Trends Are Truly Developmental in Nature.