What is the method called that measures characteristics for only part of a population?

The method that measures characteristics for only part of a population is known as sample surveys. In this approach, a subset of individuals from the larger population is selected to participate in order to gather data and make inferences about the entire population. Sample surveys are widely used because it is often impractical or impossible to collect data from every single member of a population due to factors such as cost, time, or accessibility issues.

This method is particularly useful in fields such as market research, social science, and health studies, where researchers aim to draw conclusions about a larger group based on the analysis of a smaller, representative sample. By employing statistical techniques, researchers can estimate the characteristics of the total population with a certain degree of accuracy and confidence.

In contrast, a census involves measuring characteristics across the entire population, population analysis refers to examining the demographic and socio-economic trends within a whole population, and descriptive statistics are concerned with summarizing and describing the main features of a dataset without necessarily sampling. These alternatives do not fit the definition of measuring only part of a population.