Spreadsheet or Database? Let’s be honest about our preferences. Given a pile of data to work with your first click will be the one that opens Excel. Databases are great for validation but they are lousy at maths so we in the GRTMPS team try to offer you the best of both – so you can use the input database to protect yourself from time wasting over undefined codes, but use a spreadsheet to manipulate data.  The tool for passing data in and out of the model database via Excel is called SSI – for SpreadSheet Import.