National EMSC Data Analysis Resource Center
Fortunately, you don't have to collect information for evey member of your population. There is a much more efficient and cost-effective way to gather your information. This method is called 'probability sampling.' If designed and implemented well, probability sampling will yield accurate results about your population.
A ‘probability sample’ is:
- A subgroup of the entire population chosen using random selection.
Many times, the term 'random selection' is taken to mean 'haphazard selection.'
However, ‘random selection’ is:
- A technical term that means each eligible subject has a specific and known probability of being included in your sample.
There are several types of probability sampling, such as: