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Database documentation

Entity-Relations Diagram

Simplified ERD of the CHIPS DB

Recording Measurement Errors

The following protocol has been established for recording measurement errors:

• identify the analytical setups; each of them is recorded in the machines table, specifying the type of chemical analysis, the laboratory and the model of device used.
• identify their characteristics (i.e. measurement errors); for each analytical device listed in the machines table, for each chemical element listed in the elements table, and for a given range of values, the relative measurement uncertainty is expressed in the uncertainties table. The query result in Figure 2 shows how these values are organised. Uncertainties 151 to 154 represent the relative errors of the Centre de Recherches Pétrographiques et Géochimiques (CRPG) laboratory’s ICP-MS analyser for the element Yttrium. For a content of more than 50 mg.kg^-1, this error is 5%. It increases to 15% for a measured content of between 1 and 50 mg.kg^-1, and up to 100% for measured contents of less than 0.1 mg.kg^-1.

View built on the machines, elements and uncertainties tables, showing the relative measurement uncertainties depending on the analytical setup and the measured amount range