Survey research and longitudinal studies require _____ sample sizes, which can be challenging to obtain.

In survey research and longitudinal studies, large sample sizes are essential to ensure the findings are statistically significant and generalizable to the wider population. Large sample sizes help in achieving a more accurate estimate of population parameters, reducing sampling error and increasing the reliability of the results. This is particularly important when trying to capture the effects of variables over time in longitudinal studies, as well as addressing the variability that naturally occurs in different populations.

Large samples allow researchers to identify trends and patterns more effectively, as they provide a more comprehensive representation of the population being studied. Moreover, when dealing with diverse subgroups within a population, larger sample sizes ensure that there are enough respondents in each subgroup to allow for meaningful comparisons and analyses. As a result, collecting large sample sizes is a common challenge in both survey and longitudinal research, but it is necessary for reducing bias and enhancing the robustness of the research findings.