How effective is the Advertising Standards Authority?

I should start this post with two big caveats:

1. My purpose is not to criticise the ASA, which in my experience is efficient and rigorous. If there are limitations, they may well stem from circumstances, which I hope to explore here.
2. This isn’t a particularly scientific analysis. It is not a prospective study, just a look at a large number of complaints and what happened to them.

The dataset comprises 74 complaints I have made to the ASA about misleading health-related claims, between July 2014 and January 2019. All but two related to advertisers’ own websites; one was a magazine ad, and another involved a paid-for ad by a chiropractic clinic on a local newspaper website. Here is how they were distributed (in no particular order):