A representative sample is a subset of a population that seeks to accurately reflect the characteristics of the larger group. For example, a classroom of 30 students with 15 males and 15 females ...

The danger of sampling bias is that it can result in a biased sample of a population (or non-human factors) in which all individuals, or instances, were not equally likely to have been selected.

Let’s apply the idea of sampling to the population of beetles above! The sample below is just a small portion of the original population: To illustrate why sampling works, look at the two populations ...

Consider the example in the section "Stratified Sampling". The study population is a junior high school with a total of 4,000 students in grades 7, 8, and 9. Researchers want to know how much these ...

Oversampling is the practice of selecting respondents so that some groups make up a larger share of the survey sample than they do in the population. Oversampling small groups can be difficult and ...

Polling organizations correct for these nonresponse biases by adjusting the sample to match the population, but such adjustments can never be perfect because they only correct for known biases.

In presidential elections, even the smallest changes in horse-race poll results seem to become imbued with deep meaning. But they are often overstated. Pollsters ...