UK NEQAS for Trace Elements

Measurements of performance are based on deviations of results from target values. These deviations are used to calculate a Z-score. Measurement of performance is based on deviations of results from target values. These deviations are used to calculate Z-score.

• Z-score of up to +/-2 indicates acceptable performance and a score of more than +/-3 indicates unsatisfactory performance. 
• A Z-score between -2 and -3 or +2 and +3 indicates borderline performance

More information on Z-scores and how to interpret them can be found in the education-literature section

The persistent poor performance criteria

3 or more Z-scores >2 from the last 6 samples (covering span of 3 months)

2 or more Z-scores > 3 from the last 4 samples (covering span of 2 months)

More than 1 blunder per scheme year

More than 2 non-returns in the last 12 months without providing an explanation

Annual report

An annual report is prepared within one month of the release of the final report for of the last distribution in the scheme year (March). This is made available for download from the website by each participating laboratory and includes the final data set after all corrections and amendments have been made.

UK NEQAS Guildford Peptide Hormones

The reports for the UK NEQAS Guildford Peptide Hormone’ scheme are structured to best utilise the ‘ABC of EQA’ scoring system, so you are able to see at a glance if your laboratory is performing well.

A is for Accuracy (total error)

B is for Bias

C is for Consistency of bias

The poor performance criteria:

• B score >25 or <-25
• C score >25

Persistent poor performance criteria

• B and/or C scores are outside the performance criteria for 3 consecutive distributions
• If laboratory fails to return results for 3 or more distributions in 8 months period , without notifying the UK NEQAS centre of change in participation
• Errors caused by sample mislabelling cannot be corrected because a similar error could be made on patient samples
• Reporting incorrect results will be recorded and reviewed annually