In december 2001 the department of veterans affairs announced that it would begin paying benfits to soldiers suffering from lou gehrigs disease who had served in the gulf war. this decision was based on analysis in which the lou gehrigs disease incidence rate( the proportion devolping the disease) for 700,000 soilders sent to the gulf between august 1990 and july 1991 was compared to the incidence rate for the 1.8 million other soilders who were not in the gulf during this time period. based on this data, explain why it is not appropriate to perform a formal inference procedure ( such as the two sample z test ) and yet it is still reasonable to conclude that the incidence rate is higher for gulf war veterans than for those who did not serve in the gulf war.