Descriptive research can be divided into the following two categories:
(a) Cross-sectional studies
Cross-sectional study is a study involving a sample of elements from the population of interest at a single point of time. It is a study concerned with a sample of elements from a given population. Such sample may deal with households, dealers, retail stores and other entities. Information/data on a number of characteristics are collected from the sample elements. Such data are analyzed for drawing conclusions. Cross sectional studies include field studies and surveys.
Field studies are conducted is the life situations such as schools, factories, institutions, etc. Here, the inter-relations among variables are studied under real setting. The cross-sectional analysis involves counting the simultaneous occurrence of the variables of interest. Field studies have certain merits and limitations. The important merit is that such studies are close to real life and cannot be criticised on the ground that they are away from real settings or are artificial. Field studies are also socially significant. However such studies are scientifically inferior to laboratory and field experiments. There is also lack of precision in the measurement of variables.
Cross-sectional study is possible through survey. Survey research is wide in scope. Detailed information can be collected from a sample of large population. This method is also economical as more information can be collected per unit of cost. The time required for sample survey is also less than a census-inquiry. However, in survey research, more importance is given to information collection and not to in-depth analysis. Secondly, survey research needs more time and money when conducted on a large scale.
(b) Longitudinal studies
Longitudinal studies are based on panel methods and panel data. A panel is a sample of respondents who are interviewed not only once but thereafter from time to time. Here data to be collected relate to same variables but the measurements are taken repeatedly. For example, purchase of grocery products by families/ households at regular intervals. Such data will reflect/indicate change in the buying behaviour of families/households.
There are many advantages and limitations of panel data. Panel data are suitable when the researcher undertake detailed analysis. Similarly, panel data are more comprehensive as compared to data collected from individual families. Finally, panel data collected is more accurate as compared to data collected through survey. These advantages of panel data improve the quality of research findings and conclusions.
There are certain limitations of panel data. For example, panels used for data collection may not be representative samples. Panel members may not be co-operative or may leave the panel membership. As a result, the representative character of the original sample may be adversely affected. Secondly, panel members may report wrong data. Their interest may reduce gradually and they may supply information in a casual manner. Their sense of participation/responsibility may reduce. This will affect the quality of data and also of findings.