 Dear students, we have studied two dimensions of social research, use an audience of research and then a purpose of research. Now we are going to study the third dimension of social research which is time in research and on the basis of the time in research, we categorize two types of research, cross-sectional research and longitudinal research and furthermore in longitudinal research, we have three type of research studies, panel study, cohort study and time series research. Now let's see what is cross-sectional research. Cross-sectional research is a type of research in which the researcher collects the data from the respondents at point in time. In cross-sectional research, we do the cross-sectional research because cross-sectional research are cost effective, required less time and exploratory and descriptive in nature and most of applied researchers are as well cross-sectional in nature. So what are the limitations of cross-sectional research? On the basis of the results of cross-sectional research, we cannot generalize the results. On the basis of longitudinal studies results, we can generalize the results and based on the data from a specific population or area, cross-sectional research research is based on a particular area's data set and results can be the subject of social environment and political situation. For example, if we talk in our own country, then if we don't study at national level, then our socio-political situation is very different from Punjab and Khyberprashtun of Sindh and Balochistan. So until we don't study at national level, then we cannot generalize the results at national level. In cross-sectional studies, the researchers mostly study knowledge, attitude and practices. The cross-sectional studies are mostly based on cap studies, which we do knowledge, attitude and practices studies. In cross-sectional studies, different social issues such as knowledge, belief, attitude and behavioural practices are based on those issues. So in cross-sectional studies, there is no intervention. There is very little cross-sectional studies, no intervention based studies. Intervention based studies are mostly longitudinal in nature. So in the next module, we will talk about longitudinal studies.