Panel Survey
This a type of survey method that involves repeated interviews of a group of people over a specific period of time. It is used to track progress or evolution over time. In other words, when you study Net Profit Margin (NPM) of banks (Say 4 banks) over a period of time (2018 -2020)
You data will look like this:
| Banks | Time | NPM |
| FCMB | 2020 | 50% |
| FCMB | 2019 | 55% |
| FCMB | 2018 | 51% |
| First Bank | 2020 | 60% |
| First Bank | 2019 | 70% |
| First Bank | 2018 | 55% |
| Fidelity Bank | 2020 | 45% |
| Fidelity Bank | 2019 | 50% |
| Fidelity Bank | 2018 | 60% |
| Zenith Bank | 2020 | 80% |
| Zenith Bank | 2019 | 70% |
| Zenith Bank | 2018 | 75% |
Longitudinal Survey
It is another word used to describe panel survey. It refers to any study that examines the same group of people over a period of time.
Cross-sectional survey.
This is refers to data collected by observing many subjects such as individuals, firms, countries at the same point in time or without regard to differences in time. Here data is obtained at a particular point in time. The analysis of cross-sectional data usually consists of comparing the differences among the subjects. For example, if you are studying the net profit margin (NPM) of four banks in 2020 only. You will have a data that look like this:
| Banks | Time | NPM |
| FCMB | 2020 | 50% |
| First Bank | 2020 | 60% |
| Fidelity Bank | 2020 | 45% |
| Zenith Bank | 2020 | 80% |
This is what we called cross sectional data study since you are studying Banks at a particular point in time (2020).
