Discuss the advantages and disadvantages of each of the following approaches in setting standard costs: (a) setting ideal standards vs. attainable standards. (b) holding the purchasing department responsible exclusively for material price variances and nothing else vs holding them accountable for some index which includes material price variance plus variances (favorable and/or unfavorable) in material usage variances. (c) analysis of individual variances vs analysis of groups of variances, including the interplay between variances like labor cost + labor quantity variances?