QC/QA Flashcards
A measure of tendency. It is associated with symmetrical or normal distribution
Arithmetic Value
Other name for Arithmetic Value
Mean or Average (x)
A measure of dispersion of values from the mean. It helps describe the normal curve. A measure of the distribution range. It is the most frequently used measure of variation
Standard Deviation (SD)
A percentile expression of the mean; index of precision
Coefficient of Variation (CV)
Called the standard deviation squared; a measure of variability. It represents the difference between each value and the average of the data
Variance (V)
Called the standard deviation squared; a measure of variability. It represents the difference between each value and the average of the data
Variance (V)
Are errors encountered in the collection, preparation and measurement of samples including transcription and releasing of laboratory results
Variations
3 Types of Error
- Random Error
- Systematic Error
- Clerical Error
-Random errors may be caused by variations in technique
-Error varies from sample to sample
-Causes include instrument instability, temperature variations, reagent variation, handling techniques, and operator variables
RANDOM ERROR
-Error always in one direction (may be constant or proportional).
-may be due to several factors, including poorly made standards, reagents, instrumentation problems, poorly written procedures, or inadequate staff training.
SYSTEMATIC ERROR
Another reason for outliers in method comparison studies and in daily practice is mistakes (sometimes termed blunders) or clerical errors. elements. In the past, this type of error usually arose in relation to manual transfer of results. Today, this kind of error typically is related to computer errors originating at interfaces between computer systems. Errors on test order forms or errors related to handling of order forms appear to occur relatively frequently (1% to 5% of recorded cases have been revealed in systematic studies). In the postanalytical phase, inappropriate interpretation may take place (e.g., in relation to erroneous reference intervals).
CLERICAL ERROR
TWO VARIATIONS- SYSTEMATIC ERROR
- CONSTANT ERROR
- PROPORTIONAL ERROR
exists when there is a continual difference between the test method and the comparative method values, regardless of the concentration
CONSTANT ERROR
exists when the differences between the test method and the comparative method values are proportional to the analyte concentration
PROPORTIONAL ERROR
Most Commonly used chart for QC recording
Shewhart-Levey Jennings Chart
It will group any series of measurement in the same sample in a cluster around the mean in a bell shaped curve
Gaussian Curve
Plotted with the accumulated differences from the mean of individual values with the middle value being zero
Cumulative Sum Graph
-With x and y axis
-A 2-mean chart drawn at right angles to one another with the one set of values on one axis another set of values on the other axis
Youden Plot
It is formed by control values that either increase or decrease for six consecutive days
Trend
It is formed by control values that distribute themselves on one side or either side of the mean for consecutive days
Shift
These are control values that are far from the main set of values. Highly deviating values. Caused by random and systematic errors
Outliers
What are the two interpretation of results
- In Control
- Out of Control
a set of control and patient specimens assayed, evaluated and reported together
ANALYTICAL RUN
most commonly used patient based-QC technique, the difference between two consecutive measurements of the same analytes on the same individual
DELTA CHECK
used to measure systematic errors or inaccuracy caused by substances other than the analyte.
INTERFERENCE EXPERIMENTS-
the concentration range over which the measured concentration is equal to the actual concentration without modification of the method
LINEAR/DYNAMIC RANGE
the absurd value, helps detect sample contamination or dilution, inadequate sample volume, inadequate reagent volumes, sudden major problems with the method, or incorrect recording or transmission
PHYSIOLOGIC LIMIT
It includes effective test request forms, clear instruction for patient preparation and specimen handling, appropriate turn-around time for specimen processing, testing and result reporting, appropriate reference ranges and intelligent result reports
QUALITY PATIENT CARE
it is a value obtained by observation or measurement of a particular type of quantity on a reference individual
REFERENCE RANGE
is the ability of an analytical method to maintain accuracy and precision over an extended period of time during which equipment, reagents and personnel may change.
RELIABILITY
is the ability of the analytical method to detect the proportion of individuals with the disease.
DIAGNOSTIC SENSITIVITY
is the ability of the analytical method to detect the proportion of individuals without the
disease.
DIAGNOSTIC SPECIFICITY
