{"id":629,"date":"2024-06-19T09:14:46","date_gmt":"2024-06-19T06:14:46","guid":{"rendered":"https:\/\/sisu.ut.ee\/measurement\/self-test-10-5-b\/"},"modified":"2024-06-19T09:14:46","modified_gmt":"2024-06-19T06:14:46","slug":"self-test-10-5-b","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/measurement\/self-test-10-5-b\/","title":{"rendered":"Self-test 10.5 B"},"content":{"rendered":"
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<\/p>\n\n

Here you can test your understanding of the single-lab validation approach and your ability to apply it in practice.<\/p>\n<\/div>\n\n

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This exercise is based on exercises 10.2 and 10.3, it is their combination.
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\r\nA laboratory wants to estimate the measurement uncertainty of protein content determination in different foods. For this protein content in a control sample of smoked sausage was determined repeatedly during a time period of almost one year. Every day when this smoked sausage was analysed only one parallel measurement was made. The following results were obtained:
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Week<\/strong><\/td>Result\u00a0(g\/100g)<\/strong><\/td><\/tr>
3<\/td>18.1<\/td><\/tr>
5<\/td>20.5<\/td><\/tr>
11<\/td>18.3<\/td><\/tr>
14<\/td>19.1<\/td><\/tr>
15<\/td>19.3<\/td><\/tr>
27<\/td>20.2<\/td><\/tr>
34<\/td>19.7<\/td><\/tr>
41<\/td>19.5<\/td><\/tr>
42<\/td>18.6<\/td><\/tr>
48<\/td>20.1<\/td><\/tr><\/tbody><\/table>\u00a0
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\r\nIn addition the laboratory analysed two certified reference materials: Ham with protein content (19.6 \u00b1 0.6) g\/100g (k<\/em>=2, norm) and cheese with protein content (26.3 \u00b1 0.7) g\/100g (k<\/em>=2, norm). The laboratory has carried out four bias determinations with the following results (each found value is found as a mean from a number of parallel measurements):
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Reference\u00a0(g\/100g)<\/td>Found\u00a0value\u00a0(g\/100g)<\/td><\/tr>
26.3<\/td>26.9<\/td><\/tr>
26.3<\/td>27.2<\/td><\/tr>
19.6<\/td>20.1<\/td><\/tr>
19.6<\/td>20.4<\/td><\/tr><\/tbody><\/table>\u00a0
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\r\nPlease calculate the combined standard uncertainty of the protein determination procedure (please give 1 or 2 decimals). Absolute uncertainties can be used in this case.
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