The industry has never really defined how blender accuracy is to be measured. In fact, there are two ways to look at the accuracy of a blender. One is to measure dispense accuracy relative to the setpoint for a particular ingredient and the other is to measure the amount of an ingredient relative to the total batch.
Consider, for instance, a gravimetric blender that produces 1000g batches comprised of 89% natural resin, 10% regrind and 1% color. If a blender manufacturer says its blenders are accurate to within 0.1% of the total batch, it means that the amount of any ingredient could be off by 1g. However, if you look at the color only (1% color in a1000g batch is 10g of color), an error of 1 gram is actually an accuracy of ±10% of the color setpoint.