Time-Lag Study

Differences

These methods assess three types of differences: age differences (a result of development), generational differences (a result of generational succession), and time period (a result of historical events that affect all generations equally). Longitudinal studies, which follow a group of people of the same age over time, can determine age and time period differences (but not generation, as the participants are all the same generation). Cross-sectional studies collect data at only one time; thus, any differences could be a result of age or generation (but not time period, as the time period is the same). Time-lag studies examine people of the same age at different points in time; thus, differences could be a result of the generation or time period (but not age, as age is the same). Sequential designs are the best way to separate age, time, and cohort effects. For example, a time-lag study might study several age groups over time. However, a change across all ages, usually interpreted as a time effect, could still be a cohort effect if the cohort change has been continuing for many years. For this reason, some authors have concluded that it is impossible to completely separate age, cohort, and time effects even with sequential designs. Most researchers agree that it is most important to separate age and cohort effects, as time period is a less important effect.

Thus, time-lag studies are the best method for examining generational (or birth cohort) differences. Most research and theorizing suggest that historical events and cultural trends have the most impact on the attitudes of children and adolescents; thus, generational effects are stronger than time period effects. For example, the large changes in sexual attitudes and behavior found in a time-lag study headed by Brooke Wells are primarily driven by generational change, as people tend not to change their views on sexuality much once they are past young adulthood.

Time-lag studies illustrate how historical changes in culture affect individuals. Recent research and theory in psychology have recognized that environments vary between countries and regions, producing differences in personality, emotion, perception, and behavior. Environments vary over time and generations in a similar way (for example, the United States in the 1950s was a different environment than the United States in the 2000s). The time-lag method makes it possible to study generational change scientifically, separating the effects of age and generation (as a cross-sectional study, with data collected at the same time, cannot do).

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