7.7.1
| It is not recommended that institutions use spreadsheet tools for the usage of material models and the production of metrics used for regular decision-making. More robust systems are preferred. Nevertheless, if spreadsheets are the only possible modelling environment available initially, the standards in 7.7.2 must apply, at a minimum.
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7.7.2
| Spreadsheet implementation should follow a quality standard as follows:
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| | (i) | The spreadsheet should be constructed with a logical flow, |
| | (ii) | Formulae should be easily traceable, |
| | (iii)
| Formulae should be short and constructed in a way that they are easily interpreted. It is recommended to split long formula into separate components, |
| | (iv) | Tables should include titles, units and comments, |
| | (v)
| Inputs should not be scattered across the sheets but they should be grouped in one worksheet/table, |
| | (vi) | Hardcoded entries (i.e. fixed inputs) should be clearly identified, |
| | (vii)
| Tabs should be clean, i.e. when the implementation is completed, all work in progress should be removed, |
| | (viii) | Instructions should be included in one or several tabs, and |
| | (ix)
| Wherever suitable, cells should be locked and worksheets protected, preferably by password.
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7.7.3
| Models implemented in spreadsheets that deviate from the above criteria must not be employed for regular production.
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7.7.4
| To ensure their robust implementation, spreadsheet tools must include consistency checks. Common consistency checks include: (i) computing the same results through different methods, (ii) ensuring that a specific set of inputs leads to the correct expected output values, and (iii) ensuring that the sensitivities of outputs to changes in inputs are matching expected values.
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7.7.5
| If an institution employ spreadsheets for regular production, a rigorous maker-checker process must be implemented and documented. The review of spreadsheet tools must be included in the scope of the independent validation process. In addition, a clear version control should be implemented.
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