What is what does it mean when sampling is done without replacement?

When sampling is done without replacement, it means that each individual in the population can only be selected once to be part of the sample. In other words, once an individual is selected and included in the sample, they are removed from the population and cannot be selected again.

This method of sampling is often used in situations where it is important to ensure that each individual in the population has an equal chance of being selected for the sample. It also helps to avoid duplication of individuals in the sample, which could bias the results.

Sampling without replacement can be contrasted with sampling with replacement, where individuals are selected randomly from the population and then placed back into the population before the next selection is made. This allows for the same individual to be selected multiple times in the sample.