A couple of days ago, I wrote that people often dismiss the need for Quality Assurance by saying, "These are good developers. We don’t need to test their code."

Of course, I know from experience that the best developers have errors in their code. I also know that it seems easier for me to see errors in other people’s work than in my own.

It turns out that I’m not the only one who experiences that. According to this blog post by Dorothy Graham, some research shows that people tend to find only about 1/3 of their own errors on initial inspection.

I think that’s a powerful justification for an investment in Quality Assurance.

Are any of you familiar with this research or statistic? I’m planning to look more into Capers Jones’ research and see how it applies to the value of Quality Assurance.