To understand Castleman disease, it helps to know about the bodyâs lymph system. Lymphoid tissue, also known as lymphatic tissue, is the main part of the immune system. It is formed by different types of cells that work together to help the body fight infections.
Observation Systems International Program. Demography, the science of human population (or more specifically, the study of population structure. and processes), draws together research from a number of disciplines, including economics, sociology, geography, public health, and genetics. In addition to the environmental impacts of.
1 Population and sample. In statistics, a population is an entire set of objects or units of observation of one sort or another, while a sample. is a subset (usually a proper subset) of a population, selected for particular study (usually because it is impractical. to study the whole population).