What approaches do scientists use to measure behavior in adult development and aging research?

• Measures used in research must be reliable (measure things consistently) and valid (measure what they are supposed to measure).

• Systematic observation involves watching people and carefully recording what they say or do.

Two forms are common: naturalistic observation (observing people behaving spontaneously in a real-world setting) and structured observations (creating a setting that will elicit the behavior of interest).

• If behaviors are hard to observe directly, researchers often create tasks that sample the behavior of interest.

• Self-reports involve people’s answers to questions presented in a questionnaire or interview about a topic of interest.

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Most research on adults has focused on middle- class, well-educated European Americans. This creates serious problems for understanding the development experiences of other groups of people.

What are the general designs for doing

research?

• Experiments consist of manipulating one or more independent variables, measuring one or more dependent variables, and randomly assigning participants to the experimental and control groups. Experiments provide information about cause and effect.

• Correlational designs address relations between variables; they do not provide information about cause and effect but do provide information about the strength of the relation between the variables.

• Case studies are systematic investigations of individual people that provide detailed descriptions of people’s behavior in everyday situations.

What specific designs are unique to adult

development and aging research?

• Age effects reflect underlying biological, psychological, and sociocultural changes. Cohort effects are differences caused by experiences and circumstances unique to the generation to which one belongs. Time-of-measurement effects reflect influences of the specific historical time when one is obtaining information. Developmental research designs represent various combinations of age, cohort, and time-of-measurement effects. Confounding is any situation in which one cannot determine which of two or more effects is responsible for the behaviors being observed.

• Cross-sectional designs examine multiple cohorts and age groups at a single point in time. They can identify only age differences and confound age and cohort. The use of extreme age groups (young and older adults) is problematic in that the samples may not be representative, age should be treated as a continuous variable, and the measures may not be equivalent across age groups.

• Longitudinal designs examine one cohort over two or more times of measurement. They can identify age change but have several problems, including practice effects, dropout, and selective survival. Longitudinal designs confound age and time of measurement. Microgenetic studies are short-term longitudinal designs that measure behaviors very closely over relatively brief periods of time.

• Sequential designs involve more than one cross­sectional (cross-sequential) or longitudinal (longitudinal sequential) design. Although they are complex and expensive, they are important because they help disentangle age, cohort, and time-of-measurement effects.

• Meta-analyses examine the consistency of findings across many research studies.

What ethical procedures must researchers

follow?

• Investigators must obtain informed consent from their participants before conducting research.