Quality Control Concepts

Accuracy

Closeness to the true value or the measure of truth of a result.

 

Assay Mean

A peer group specific value printed on the assay sheet.

 

Calibrator

A material that is used to adjust instrumentation that is based on or traceable to a reference preparation or material, and whose values are determined by acceptable reference methods.

 

Coefficient of Variation (CV)

The Standard Deviation expressed as a percentage of the mean.               

                   

Controls

Materials that are solutions of chemically stabilized red cells, white cells and/or analogs, and platelets. The most important characteristics of control materials are their stability and physical similarity to real patient samples. They are used to monitor the performance of an instrument or procedure.

 

Gaussian Distribution

A bell-shaped distribution of results from a normal sample population.

Late Data

Data received by the CBC-Monitor QC Department after the cutoff date (6th of month). Late data will be accepted and analyzed and will be processed and reported on the next month's cycle. The statistics from your Primary Parameters will appear on your next Comparison History Report under the correct monthly heading.

 

Linearity Check

A check or test to confirm that an instrument or method is linear over its published working range.

 

Mean

The mathematical average for a group of data points.
                       

Mean Difference

The difference between the peer group mean and your mean.

 

Patient Controls

Replicate testing of pooled or designated patient blood samples at specified times during a specific period of time.

 

Peer Group

A grouping of similar instrument types for comparison purposes.

 

Precision

The expression of the variability of analysis, or an indication of the amount of random error that exists in an analytical process.

 

Precision Index (PI)

The ratio of Your % CV to the Group % CV. PI is a measure of relative precision.
                

 

Primary Parameters

Those parameters that are mainly measured parameters and that are used as a basis for calculations of other parameters. They are: WBC, RBC, HGB, HCT, MCV, PLT, MPV, NEU% (GRAN%), LYM%, MON%, EOS%, BAS%, etc.

 

Rejected Data

Data that is excluded from your lab's data and the peer group's data (R) or is only excluded from the peer group's data (R*).

 

Shift

An abrupt change in the pattern of data points on a plot, graph, or chart of data points.
                  

 

Standard Deviation (SD)

A measure of the dispersion of a group of values around a mean, expressed in the units being measured. Since 95 % of all results in a normal population fall within 2 SDs of the mean, +2 SD is considered an acceptable laboratory standard.

                               

 

Standard Deviation Index (SDI)

The number of Group Standard Deviations that Your Mean differs from the Group Mean. SDI is a measure of relative accuracy.
                

Trend

A gradual change in the pattern of data points on a plot, graph, or chart of data points.
           

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X	B

The principle and application of moving averages to quality control statistical data. This is very similar to the daily average except that statistical smoothing techniques are used in calculating the moving average to reduce the effect of individual values on the average.

 

Z-Score

The same as Standard Deviation Index (SDI).