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Proficiency testing tools
The calculations PT providers and laboratories do every round, done for you and shown step by step. Everything runs in your browser: nothing you enter is sent or stored.
z, z′, ζ and En calculator
Score a PT result and see its band, with the working shown.
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Algorithm A calculator
Robust mean, robust SD and u(xpt) from a list of results.
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Homogeneity check
Duplicate results for 10 items: sw, ss and the 0.3 σpt verdict.
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Youden plot
Plot z scores for two samples and spot systematic error.
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PT formula sheet
Every score, robust statistic and acceptance criterion on one printable page.
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Want to know why the numbers come out the way they do? The free course explains each method with worked examples and case studies.
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