Is this true? I usually bill by the hour, but I have to say that there’s always some awkwardness about this aspect of consulting. Compared the typical hourly rates charged by statistical consultants, my impression is that I charge more but that I bill for far fewer hours–partly because I do consulting as an extra, not as my main job, so I’m typically trying to keep the hours limited.
Maybe a fixed charge would be better, but the trouble is that it’s not always clear to me what exactly is needed. Or maybe there should be two stages: first a fixed charge where the product is an assessment of the problem, then another fixed charge for the main projects. Or maybe charge an hourly rate for the little problems and a fixed rate for the big ones. It’s something to think about. It would be great to get enough money from consulting to really support some of my research efforts.