CAS PS 241 Lecture 4: Study Designs and Genetics
26 Oct 2018
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Cross-sectional design: simultaneously compare different age groups, looking for age differences. Disadvantages: cohort effect: doesn"t control for cohort effects (ie. historical variables) People in cohorts differ due to environmental differences. Longitudinal design: observe the same individuals at different points in their development (age change) Disadvantage: labor intense and expensive, time consuming, instruments used for measurements might become obsolete in the time it takes to complete the study. Selective attrition: people might drop out (especially those who score lower on certain measurements, like iq) Practice effects: people might perform better on tasks throughout the course of the study, because of practice rather than as an effect of variables that are being controlled for. A longitudinal study that is replicated over different cohorts. Microgenetic design: a small number of subjects repeatedly observed over a short period of time in order to study change in a developmental process. Phenotype: the expression of an individual"s genotype in observable and measurable behaviors.
