Non-probability sampling: Inferences about the population cannot be made from the sample when using non-probability techniques. Statistical tests cannot be used with these methods.

Population of interest: The group of people who will be surveyed and who the researcher is interested in gaining information about.

Probability sampling: A sampling technique in which the probability of getting any particular sample may be calculated (Wikipedia 2006).

Sample: A subset of the population of interest.

Sample frame: a comprehensive list of the population of interest.

Sampling: The selection of a subset of individuals from a population to form a sample.

Sampling error: The calculated difference between the sample values for your questions and the population values.