Excel spreadsheets, we all know them, most of us use them, and some of us develop and validate them. And sometimes, they can be the bane to your existence. Don't worry though. In this blog, we will enlighten you with best practices for validating these wondrous spreadsheets.
First of all, an answer to the question: why do we validate Excel spreadsheets? There are multiple reasons:
Excel spreadsheets may be used to automate calculations, which in turn have to be validated because you need to be sure that your calculations are correct.
They may contain critical data like test results.
A completed spreadsheet is considered an electronic record and must as such be Annex 11 and CFR 21 Part 11 compliant.
Excel AND Excel spreadsheets are considered to be software according to GAMP5, which can immediately be used to assist during validation.
1. Keep it secure
A spreadsheet is a file, both as an empty template or as a completed electronic record. And files have to be kept somewhere, and if possible at all, somewhere secure. Let me introduce you to the first one in our bounty of best practices:
Store your validated spreadsheets on a network share with read-only access right for the end-users. This means that end-users should not be able to save or add files in the network share and cannot modify files.
Similarly, assign write rights for the network share for the assigned responsible person.
End-users should only be able to fill in permitted cells, on which I will tell you a bit more later on.
End users can only print and save to a protected data repository (which could be a different network share).
Assuming our files are now stored in a safe place, let’s take a look at which protective measure can be taken for the spreadsheet itself. Yup, you guessed it, more best practices coming up:
Lock all cells containing calculations, which means adding a password to unlock these fields. This code should only be available to the responsible person.
Protect your workbook structure by adding a password as well (this can be the same if you want to have an all-round Excel spreadsheet password).