What's a sample, and why should I care? Knowing whether your data is from a sample or a population helps you understand what questions to ask. Data from samples is easier to get, but it's also potentially biased. So with samples you want to know whether the sampling methods were good--meaning that they would not bias your data. When you get data from the population, every member or part of the relevant group or category is included in your data. This is thorough, but it's also hard to do. Most of the time, we deal with samples, meaning we pull data from just a part of the population. This makes data easier to obtain, but it can create its own set of challenges because data drawn from a sample may be biased if the sample is not random.