Small Changes in Code are Dangerous

Reading Code Complete, I was very interested by the graphical showing how the smallest changes are the ones that are the more likely to contain errors.

This graph shows that changes of 4 lines have a 75% chance of introducing new errors.

As outlined in that particular part of the book (Chapter 24.4 - "Refactoring Safely"), as programmers we tend to treat small changes casually. We all know that those one line changes can't possibly break, right?

How ironical?

So let us all be carefull with minor changes, or we'll get certified on the "Works on My Machine" Certification Program.