Methodology: The research methods used for a study.
Respondent: A participant in a research process.
Sample: The number of people actually participating in a study.
Random sample: A sample of respondents chosen from the population at random. Also known as probability sample.
Quota Sample: A sample of participants who fall into designated demographic categories (i.e. age) or have specific traits necessary for the study (i.e. buy a particular product). Not a random sample because the participants are targeted for specific reasons.
Stratified random sample: A quota sample for which each sub-sample is selected at random.
Convenience sample: A sample selection method based on who can be reached quickly, efficiently, inexpensively or easily. No attempt to verify a representative cross-section of the target audiences. Subject to significant bias.
Qualitative: Data that cannot be precisely reported as representative of a larger audience. Often used more for exploration or concept validation. Examples include focus groups, small sample studies, and informal or in-depth discussions.
Quantitative: Data that can be scientifically analyzed and given empirical value. Suggests precision of responses, projectable to larger populations. Examples include scientific (random sample) surveys among various audiences.
Statistics and Analysis
Bias: Possibility that any aspect of a study misrepresents the true situation. Possible types of bias include question bias, interviewer bias, interviewer errors, environmental (external) bias and various forms of sample bias: non-response, list errors, sub-group absence or dominance.
Confidence interval: The range around a survey result for which there is a specific statistical probability that it contains the true margin of error. Most commonly in practical studies: 95%.