QC/QA

A measure of tendency. It is associated with symmetrical or normal distribution

Other name for Arithmetic Value

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

A percentile expression of the mean; index of precision

Called the standard deviation squared; a measure of variability. It represents the difference between each value and the average of the data

Called the standard deviation squared; a measure of variability. It represents the difference between each value and the average of the data

Are errors encountered in the collection, preparation and measurement of samples including transcription and releasing of laboratory results

3 Types of 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

-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.

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).

TWO VARIATIONS- SYSTEMATIC ERROR

exists when there is a continual difference between the test method and the comparative method values, regardless of the concentration

exists when the differences between the test method and the comparative method values are proportional to the analyte concentration

Most Commonly used chart for QC recording

It will group any series of measurement in the same sample in a cluster around the mean in a bell shaped curve

Plotted with the accumulated differences from the mean of individual values with the middle value being zero

-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

It is formed by control values that either increase or decrease for six consecutive days

It is formed by control values that distribute themselves on one side or either side of the mean for consecutive days

These are control values that are far from the main set of values. Highly deviating values. Caused by random and systematic errors

What are the two interpretation of results

a set of control and patient specimens assayed, evaluated and reported together

most commonly used patient based-QC technique, the difference between two consecutive measurements of the same analytes on the same individual