Glossary terms for 'Q'
| Quality control | The processes to ensure that the conduct of a study, including enrollment, measurements, laboratory procedures, and data management and analysis, are of the highest quality. For example, the investigators controlled the quality of data collection by preparing explicit written procedures for all study measurements in an operations manual and intermittently observing study staff to make sure they followed them. |
| Questionnaire | A measurement instrument consisting of a series of questions to obtain information from study participants. Questionnaires can be either self-administered or administered by study staff. For example, the Block Food Frequency Questionnaire asks about usual intake of 110 food items to assess intake of multiple nutrients and food groups. |
Glossary material from Hulley SB et al. Designing Clinical Research, 4th ed. Philadelphia, Lippincott Williams & Wilkins, 2013.