INSTRUMENTATION DEFINITION OF TERMS: Energy: entity that this transmitted by electromagnetic waves Wavelength: defined as the distance between two successive peaks Nanometer: unit expression of wavelength Frequency: number of waves that passes a point of observation per one unit of time Six Sigma: a way of improving product processing to _ _: used to check if there are significant differences between present set of values to that of past values on the sample of same individual. Improper calibration, reagent deterioration, contaminated solutions, instability of both samples and solutions SOURCES OF ERROR By chance errors: mislabeling, pipetting error, fluctuations in temperature & voltage TYPE OF ERROR RANDOM - Tests for imprecision T-test: this is used to assess if there is a statistical difference between the means of 2 groups of data F-test: this is used to assess if there is a statistical difference between the SD of 2 groups of data Shewhart Levey-Jennings Chart: most widely used QC chart Trend: six or more consecutive values that either increase or decrease gradually (will cross the mean) – main cause: reagent deterioration Shift: six or more consecutive values that are distributed on one side or other side of the mean (does NOT cross the mean) – main cause: instrument calibration is improper WESTGARD RULES Coefficient of variation: mean expression in percentile Mean: average of a set of values (mean = Σx/n) Median: midpoint of a set of values Mode: the most frequent among all values/data Standard Deviation: it is defined as the measure of dispersion of values to that of the mean □(□−□□□□)2 Sensitivity: defined as the ability of a method to measure analytes even at its lowest concentration Accuracy: nearness of measured value to that of the target value Precision: nearness of measured values to each other Diagnostic specificity: defined as the ability of a method to detect a population of individuals absent of a disease process Diagnostic sensitivity: defined as the ability of a method to detect a population of individuals having the presence of disease Intralab QC (internal QC): control samples are run simultaneously with a patient to ensure reliability of methods and result Interlab QC (external QC): laboratories are given samples with unknown concentrations for them to test and results are compared with other laboratories thus maintaining “long term accuracy” to methods utilized. Control: a solution that resembles a human serum that is used for QC purposes only Standard: a colorless solution with known concentration of substances used for calibration Specificity: defined as the ability of a method to measure the analyte of interest ONLY. Quality control TERMS TO REMEMBER: Quality: a feature/characteristic of a product, which meets the expected criteria of a consumer (customer).
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