This document is a lecture on quality control for paramedical students. It defines key terms like specificity, sensitivity, and bias. Specificity refers to a test that measures only the intended analyte. Sensitivity indicates a test's ability to detect small concentrations. Bias is a systematic error in data collection. The lecture also discusses quality assessment, including pre-analytical, analytical, and post-analytical factors. Statistical calculations like mean, standard deviation, and coefficient of variation are explained. Quality control charts like the Levey Jennings chart are introduced to monitor accuracy and precision. Finally, systematic and random errors are distinguished.