A histogram-based method for testing an electronic converter device, such as an analogue to digital converter, includes steps of defining at least one histogram hyperbin arranged to store hits for at least one subrange of output codes; applying an input test stimulus to an input of the device to test a subrange of output codes matched to the hyperbin; and accumulating the histogram. At least two hyperbins may be provided, each bin being arranged to store hits for at least one subrange of output codes, and the input test stimulus is applied to an input of the device to test a subrange of output codes matched to one of the hyperbins. Both hyperbins may be open while the histogram is being accumulated for any subrange of output codes. The method may further involve varying the input stimulus to test another subrange.