My advisor assigned me a project using a statistical method I don't think he fully understood. It's new, one he hasn't used before, and it is in a dense, poorly written article. I have expressed to him that I felt we didn't understand it well enough, that we should consider collaborating with others to make sure the method was tenable, and that I felt it might not work. However, he blew these concerns off. When the initial results looked promising, I let it go.
A few months later, my latest results look weird as hell. I reread the article for hundredth time to see if we had missed something. I think I found it. I have good reason to believe that our data violate a key assumption of the method (not described by the authors!) and that our results are complete garbage.
The problem is that I am signed up to present these results as a poster in a few months time at a conference to which I have already been accepted and funded to attend. I don't know how I can back out with my plane and hotel already bought by the department. What do I do? Keep mum? It's wrong and I'm worried someone will find me out anyway.
I have emailed my advisor, but he is on vacation and hasn't responded yet.
Please proceed from the assumption that I am correct. I don't need to troubelshoot a scenario where everything is A OK. I need to troubleshoot the potentially terrible mistake I have made. Even though everyone in the field knows that beginning students don't design these projects, my head is on the chopping block; I am ultimately responsible for the research I put my name on.
Knowing what I know now, I won't let it get to the publishing phase before the issues I identified are resolved, but what do I do about the conference?