Technical Medical Institute, Middle Technical University, Mansour, Iraq
There are many types of data that depend on the type of research study and the type of observations taken for the purpose of the study and also depend on the type of research or research study and the desired results from the analysis of observations. One of these types of data is double longitudinal data or the so-called cross-sectional data. It is a group of ramified chains that go through the same conditions and are studied and analyzed at the same time. The idea of this data is to take observations for a certain period of time and for a certain phenomenon, such as if this phenomenon is a satisfactory condition or currency exchange rates if the subject of the study is economic or, for example, studying a type of agricultural crop that The study was agricultural, etc. The cross-sectional data is characterized by the fact that it takes the case for the studied observations and for a group of variables for the same time period, and requires that these observations have passed through the same conditions that all variables go through and for the specified time period. It generates for us what is scientifically known as cross-sectional or longitudinal double data, which works to address this leakage by conducting a scientific-statistical analysis in accordance with the type of cross-sectional data and study data as explained above, and we will include in this article some types of cross-sectional data and cases that may pass with it.