A cellular telephone case has front and back panels. At least one actuating button that can be pressed downwards is arranged on the upper side of the outside housing. The method embodiment includes calculating coil coefficients based on the set of ACS lines and then selectively manipulating a weight associated with an outlying data point to reduce the effect of the outlying data. The inner surface includes a first reflecting surface between the first end and the upper end of the inner surface and a second reflecting surface between the second end and the upper end of the inner surface. The wafer yield measures for each failure bin corresponding to one of the selected subset of device performance variables are combined, to provide a combined wafer yield measure.