The failure of startup ideas is probably one of the toughest to quantify: Failed ideas probably didn't result into a registered business. Articles on the internet all seem to refer to a paper from 2011 (http://gallery.mailchimp.com/8c534f3b5ad611c0ff8aeccd5/files...) that claims that 72% of intellectual property is not a competitive advantage.

This article (https://www.forbes.com/sites/neilpatel/2015/01/16/90-of-star...) claims that 42% of startups fail because there's no market demand. Which doesn't include startups that found market demand, but didn't offer what the market needed (e.g. market values the offer but doesn't (or too little) want to pay for it). For failed startups in general, this article mentions a failure rate of 90%, but the reasons are diverse.

As I'm focusing on the validation (and some ideation) phase, the first metric made the most sense. Thanks for being critical!