Collecting data from every single unit (e.g. human, animal, farm) of a population or category of objects.

Bacteria that normally live in or on the human or animal body without causing disease. In fact, some of these are beneficial to the host in different ways, which includes competing with other potentially pathogenic bacteria.

The probability of getting the results observed by chance alone: the higher the confidence, the less likely the results observed are due to chance. Larger sample sizes result in higher levels of confidence. Confidence levels of 90% or 95% are commonly used.