Selection bias occurs when the participants included in a study or analysis are not representative of the larger population. This can lead to skewed results and conclusions that do not accurately reflect the true situation. For example, if a survey about health habits only includes responses from gym members, it may overlook the behaviors of those who do not exercise regularly. This bias can arise from various factors, such as how participants are recruited or self-selection, where individuals choose to participate based on certain characteristics. To minimize selection bias, researchers should aim for random sampling and ensure diverse representation from the entire population being studied.