By using the word 'higher' you clearly indicate that you think that there is a quality advantage to open source software.
If you don't think there's an advantage to open source development, then I don't see what meaning you were trying to convey in your original comment.
It seems bizarre that you don't know why I'd be interested in evidence that open source projects have systematically better quality. It would be a major result with implications in project planning, system architecture, organizational philosophy etc. To date, I have never seen such evidence - only reasoned opinion which is valuable but inconclusive.
If you had evidence, I'm sure you'd have produced it by now.
It's obvious (as I stated in my first reply) that open source can sometimes produce high quality software. Another great example would be webkit.
I thought you knew of some evidence that might show why governments should choose open source, other than opinion and dogma.
I'm disappointed that it doesn't exist because it would be powerfully persuasive in furthering the cause of open source.