Final answer:
The first critical step in sampling is to determine the system of interest, identify the needed information and the goal, and make a sketch if helpful. In surveys, it involves deciding on the population to study, like conducting stratified sampling in a school survey.
Step-by-step explanation:
The first critical step in sampling is to determine the system of interest and identify which information is needed and what the goal of the sampling is. During this initial stage, it is also useful to create a sketch to visually represent the area being studied or to structure the approach to data collection. This step is essential for ensuring that the data collected will be relevant to the research question and collected in a systematic way. In cases such as collecting skin samples, one must decide which part of the skin to sample, provided that only external skin surfaces are allowed for the sampling process. For a survey, it would mean identifying the desired population. For example, if a high school principal is polling regarding policy changes for after-school activities by sampling equal numbers of freshmen, sophomores, juniors, and seniors, the principal is using a stratified sampling technique.