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Assay Troubleshooting Title
 
     
 

Example 1:  Good Assay, Bad Control

 
 

Step 1

 
  Look at the statistical QC Evaluation on the Summary Page of the Assay Report.  
 
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If QC Evaluation is "Acceptable", report the assay.  
 
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If QC Evaluation is "Inspect Assay", proceed to step 2.  
  Control Group Probability Indexes  
  Figure 1.  An excerpt from the Summary Page of the Assay Report shows the Statistical Quality Control Evaluation: "INSPECT ASSAY".  (More information on this table and Method Controls (MC) and Subpop. Distributions (SP) can be found in the Assay Report's Summary Page in the Operator’s Guide.)  
     
 

Step 2

 
 
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Flagged parameters are listed in the outlier table on the Summary Page of the Assay Report.  
  Significant Differences From Reference Assay Controls  
  Figure 2. The outlier table from the Summary Page of the Assay Report shows the flagged parameters in red.  (More information about the outlier table can be found on the Assay Report's Summary Page in the Operator’s Guide)  
 
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The statistical tables below provide more information about the statistical analysis.  
  Statistical Tables  
 

Figure 3.  An example of the Statistical Tables from the Assay Report shows the statistical comparison results for the assay parameters.  Note that the flagged parameters on the statistical tables (which appear in red) are also listed on the outlier table on the Summary Page (Figure 2).   (More information about the statistical tables can be found on the Assay Report's Statistical Tables in the Operator’s Guide.)

 
 
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Outliers can also be identified by examining the modified Levey-Jennings Charts.  
    Modified Levey-Jennings Chart  
 

Figure 4.  The modified Levey-Jennings chart shows the (Low-1) control specimen responses (adjusted, normalized and concentration) for the last thirty assays.  Note that all three responses are flagged for assay number 25 and are listed in the outlier table (Figure 2).  (More information about adjusted responses and normalized responses can be found in the Glossary.  More information about the charts can be found in the Assay Report's Graphs in the Operator’s Guide.)

 
 

Step 3

 
 

To identify the failed component, match the flagged QC parameters with the flagged parameters under each component listed in the top section of the StatLIA troubleshooting chart below (Figure 5).

 
 
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The parameters in the top section of the chart are diagnostic parameters which are used to identify the failed reagent or incubation step.  
    Assay Troubleshooting illustration  
 

Figure 5.  The illustration shows the process involved in troubleshooting an assay flagged by StatLIA.  In this example, the Low-1 (Adj-ABS) (the adjusted absorbance of the Low-1 control specimen) and Low-1 (%B/St6 ABS) (the normalized response of the Low-1 control specimen) on the report is matched to the flagged parameters on the chart (red circle) in step A.  Note that the absence of any other flagged parameter confirms that this column is the only one that matches.  The failed component is determined by reading the component header from this column in step B, which in this case is the Control Specimen (Low-1).

 
 

Step 4

 
 

To judge the effect of the failed component on the assay results, examine the parameters listed in the bottom section of the StatLIA troubleshooting chart (see below).

 
 
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The parameters in the bottom section of the chart, such as control specimen concentrations, are used to gauge the impact of the failed reagent or incubation step on the unknown concentrations.  
    Assay Troubleshooting illustration  
  Figure 6.  The illustration shows the final step in the troubleshooting process.  The gauging parameters, in this case the control specimen concentration is flagged.  This flag is due to a bad control specimen, not a bad computation of the control specimen concentration.  
 

Note:  The only gauging parameter flagged is the Control Specimen Concentration.   None of the Monitor Points or Standard Curve Probabilities (Curve Prob) is flagged.  This indicates that the standard curve and unknown results were not affected. 

 
 
 
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Copyright © 2013 Brendan Technologies, Inc.
 

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