ch 2- Research designs

cross sectional designs

• Compares different age groups at one point in time.

• Advantages: Quick, cost-effective, and allows for comparison across age groups.

• Disadvantages: Cannot track age changes over time, and results may be influenced by cohort effects (differences due to unique life experiences rather than age).

longitudinal designs

• Follows the same group of people over an extended period, collecting repeated data.

• Advantages: Tracks age-related changes, controls for cohort effects, and provides more reliable developmental trends.

• Disadvantages: Time-consuming, expensive, and affected by attrition (dropout of participants), practice effects (learning from repeated testing), and time of measurement effects (external events impacting results).

sequential designs

 to address limitations in aging research. Since age cannot be manipulated as an independent variable, researchers use sequential designs to separate age effects from cohort and time of measurement effects.

types of sequential designs

cohort

time sequential designs

cross sequential desgins

cohort sequential designs

• Compares the effects of cohort (year of birth) with the effects of age.

• Helps identify whether differences are due to intrinsic aging or external events.

• Limitation: Time of measurement effects cannot be isolated

If you want to study how people’s reading skills develop as they grow, you might have:

• Cohort 1: A group of 5-year-olds you study over several years.

• Cohort 2: A group of 6-year-olds you also study for a few years, starting after Cohort 1.

• You keep collecting data from both groups at the same time each year to compare how their reading skills develop.

time sequential designs

• Compares age effects with time of measurement effects.

• Useful for separating these two factors.

• Limitation: Cohort effects remain confounded.

SAME age DIFFERENT time periods

• Sequential: It happens in a series, step by step, over time.

• Time-based: The focus is on how things change or develop as time passes.

• Purpose: To track patterns, trends, or effects over different periods, helping to understand the cause and effect over time.

cross sequential desgins

• Examines the interaction of cohort and time of measurement.

• Helps understand how both cohort and testing time influence results.

• Limitation: Age effects remain confounded.

DIFFERENT AGES and DIFFERENT AGE GROUPS (COHORTS)

Imagine you want to study how people's attitudes toward technology change as they age. You might:

• Take a group of teenagers, adults, and older adults (the cross-sectional part).

• Follow each group for a few years to see how their attitudes change over time (the longitudinal part).