RCPAQAP has updated the report format issued to participants enrolled in the Liquid Serum Chemistry Program. The new report format follows a standard structure that will be adopted by other programs offered by the RCPAQAP.
Summary of Performance
An explanation of what is populated in the table columns in the example provided below.
- Measurand: All measurands that are performed by the participant are presented in the summary table.
- Expected Result: The expected result lists the target result for the measurand. The target result is based on the type of target source used – these are listed below.
i. Calculated ‘All method median’
ii. Calculated ‘Category median’, using the primary variable of the test method. It could be the analytical principle, measurement system, reagent or calibrator. The target source is highlighted on the result page of the measurand.
iii. Specific target – A sample with a known quantity of the measurand. A specific target is usually assigned to samples that have been tested using a reference method or have been tested by a reference laboratory.
- Your result: The result submitted by the participant.
- Review: Results flagged for review are based on the Analytical Performance specifications (APS). These are highlighted in red and are listed as ‘High’ or ‘Low’.
- Z-score /APS score: The z-score and APS scores are two types of performance indicators. The Z-score uses the mean result and SD to indicate the number of standard deviations a participant is away from the average result. The APS score uses the median and the assigned APS to calculate the APS score. Please refer to the RCPAQAP Data Analysis and Assessment Criteria Handbook, which provides a more detailed explanation on how the APS and Z-score are calculated.
The Summary of Performance also provides participants with their overall performance and indicates what measurands are marked for review.
- A – Histograms – provide a distribution of the results submitted by all participants. The blue bar represents the median or target result, and the blue circle represents the participant’s result.
- B – Lab results – illustrates the results and method categories returned by the participant.
- C – Analytical Performance Specification (APS) – The APS that has been assigned to the measurand
- D – Youden charts – represent a scatter of 2 sample results plotted against each other. The sample with the higher measurand level is on the y-axis plotted against the lower level on the x-axis. Five Youden plots are presented and illustrate from left to right, results from all participants, the participant’s method, analytical principle, measurement system and the reagent. The participant’s result is highlighted by the blue dot.
- E – Summary of results. Indicates what targets are used to compare results (Results assessed against: All results for 7-01, 7-02). The table columns represent the Sample ID, Main category assigned for result comparison (assigned as the main variable of the measurand method), median result, participant’s result, review flag (H/L), Z-score and the APS score.
- F – Levey Jennings type plot. Displays the APS score for all samples and provides an indication of the precision and accuracy of results within a survey year and/or across survey years.
- G – Linearity plot. Displays the participant result against the expected result, and provides an indication of linearity across different survey sample levels of the measurand being surveyed.
The method comparison provides participants with a breakdown of the main category assigned to the measurand and facilitates peer group comparison. This will usually be the analytical principle or the measurement system used. Categories with 4 participants or more display the median value obtained, categories with 3 or fewer participants do not present any statistical data, and otherwise illustrate the Median, SD and CV% values.
Z-scores for measurands performed by the participants is plotted on Levey Jennings type plots. The plotted values contain cumulative z-scores from previous surveys (up to 8 survey samples).