Chapter 28 Quality Control
1. Quality control is defined as the process by which one monitors analytical procedures in order to ensure the accuracy and precision of test results and thus the validity of patient results prior to their reporting.
2. Internal quality control involves establishing the mean and standard deviation for the QC material, verifying the accuracy and precision of the control material, and establishing acceptable statistical limits for each analytical method using that control.
In contrary to that, external QC involves the comparison of a lab’s assay results from unknown test samples with the mean of those obtained on the same samples by other labs.
3. a. Accuracy: measure of how closely a test result agrees with the true value for that sample. b. Precision: measure of how closely repeated measurements of a sample agree with each other. c. Reliability: measure of both the accuracy and precision of a method. d. Mean: Average of all data points
e. Median: middle data point of all data points
f. Mode: most frequent number
g. Range: the difference between high and low values in a data set h. Variance: mathematical representation of dispersion of data points i. Standard deviation: mathematical representation of dispersion of data points around the mean or peak in a data set j. Confidence intervals: refers to the limits between which a specified proportion of the data points in a data set will fall. k. Coefficient of variation: the standard deviation divided by the mean and multiplied by 100 to obtain a percentage. l. Trend: a small but steady and continuous change of the control values in one direction m. Shift: A change of the mean for the control material.
n. Central tendency: represents a large group of data points that are equal to or very nearly the same as one data point and are represented by a peak on a frequency diagram. o. Normal distribution: Implies that there are approximately the same number and...
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