Cathy O'Neil on when there's enough data to justify a data scientist in the workplace:
Too much to fit on an Excel spreadsheet. And it’s not just how much, it’s really about how high quality the data is; the best is for it to be clean and for it to not be public, or at least not generally used for the purpose that your business uses it for.
Even data that does fit in Excel can be examined more closely. Then again, if you only have that much data, your data scientist will get bored quickly.