Fractures of the spine are common and serious among women with advanced osteoporosis (low mineral density in the bones). can taking strontium ranelate ? a large medical experiment assigned 1649 women to take either strontium renelate or a placebo each day. all of the subjects had osteoporosis and had suffered at least one fracture. all were taking calcium supplements and receiving standard medical care. the response variables were measurements of bone density and counts of new fractures over three years. the subjects were treated at 10 medical centers in 10 different countries. (based on pierre j. meunier et al., "the effects of strontium renelate on the risk of vertebral fracture in women with postmenopausal osteoporosis," new england journal of medicine, 350 (2004), pp. 459-468.) (a) outline a block design for this experiment, with the medical centers as blocks.