There was no ad hominem (or ad hoc as you are now calling it). You claimed you took a course, and during that course you examined studies, and those studies confirmed;
You were asked for evidence to support such an assertion and you pointed back to your initial explanation, which I included in my post. The problem is, we were not in that class with you, we did not see those studies, and now you claim you don't have your notes, and, we assume, a link to those studies. So please, excuse us if we don't just take your word for it. And by pointing out that you can not offer a shred of evidence to support the claim is not an ad hominem, but it does show that it IS a bare assertion, because, just as the definition (which I also included in my post) points out, you are not including any supporting evidence, reasoning, or justification.
The good faith was in asking you to provide evidence to support the claim. I'm sure you would do exactly the same thing should I make a claim you don't necessarily believe in. And now you're implying you can dig out that study (I would point out you initially said studies (plural), and now you're claiming study (singular)) so since you started this by making the claim, why don't you show good faith and provide evidence to back it up?
BTW, are you going to address your "(and we saw Knox get 28 years)" comment, which was clearly intended to show Amanda got a stiffer sentence than Raffaele's 25. Unfortunately for you, Amanda's 28 year sentence included 3 years for calunnia, so her sentence for murder was identical to Raffaele's, and it did not support your claim. I get why you don't want to address this, but let's see a little good faith and honesty and concede you were wrong and Amanda's 28 years did not support your claim.