I, too, have little familiarity with the methods and results used for testing compost. I can tell you that the methods used for testing soil (dirt: primarily consisting of sand/silt/clay-mineral parent material with a relatively low % of OM) are not correlated or calibrated for testing something like compost. I've read that once soil OM exceeds 20%, that the results from common soil testing methods aren't very useful in predicting nutrient sufficiency levels. Based on that, I'd think that using those methods to test pure compost would produce results that wouldn't have much useful application. I've only ever seen a couple of compost reports and they all reported nitrogen, phosphorous, potassium etc. as a % by weight. Like the analysis for a fertilizer. They also tested and reported for things like heavy metals and pathogens, things that a gardener wouldn't want in their tomatoes.