What defines sequential sampling in a statistical context?

Sequential sampling refers to a statistical method where samples are drawn sequentially, which means that data points are collected in a sequence rather than all at once. This approach allows for a dynamic process where each sample is taken based on the results of the previous samples. It effectively enables ongoing decision-making about when to stop sampling, based on the evidence gathered.

Choosing samples over a period of time aligns well with the concept of sequential sampling, as it emphasizes that the sampling continues as needed until a particular level of confidence is achieved about the population being studied or a specific decision is made.

In this context, the other options do not capture the essence of sequential sampling. Taking a sample over a certain period naturally implies an ongoing process, while the other choices pertain to static methods of sampling or categorization rather than the dynamic nature of sequential sampling.