In this case, the researcher can look at a variety of ages, ethnicities and social backgrounds, and from this, if a large number of cases arise from any of the predetermined groups, and then further research can be done.
On the other hand, longitudinal design follows the same sample over extended periods and makes repeated observations facilitating the study of change (“Types of Research Designs”). In addition, time series is referred to as trend series that covers a cross-section of studies taken over time, and with repetition of the same question within the given population. Perfect example of this would in cases of politics where the popularity of a politician is taken using opinion polls over time to determine the peoples’ choice. As for panel studies, they follow given subjects over time to monitor changes in the subjects affiliation. As in politics, researchers stick to the followers of a politician to monitor whose loyalty wavers, and to which side. In addition, a cohort study tracks a subset of a population over time, just like in the time series, but using various, non-fixed, samples (“Types of Research Designs”). This is done by following a smaller group of the larger population, as is the case with the Vietnam War veterans. The case study method is offers in-depth look at a definite problem instead of going over a statistical survey. It is applied in testing theories such as determining the cause of