I nearly made a costly mistake once.
Starting with bad data, or just misinterpreting or misrepresenting data to your stakeholders can send your project down the wrong path and hurt your reputation. Your once compelling evidence that you've made good decisions is suddenly not as compelling as you thought. Just ask this guy, or this guy or this guy or this guy.
Data quality can make or break your project from the outset.
I nearly made a costly mistake once. I was plotting points on a map from a list of coordinates and thanks to Excel, each record had been rounded to two decimal places. Luckily, I noticed a pattern in the point distribution immediately before I went any further - all the points lined up in a perfect, even grid! A simple mistake that anyone could make that would have ruined the data interpretation and project results if I had not caught it early.
Have you learned this lesson the hard way? Share a story below.