Specialized ratios are sometimes used in specific industries. For example, the so-called book-to-bill ratio is closely watched for semiconductor manufacturers. A ratio of .93 indicates that for every $100 worth of chips shipped over some period, only $93 worth of new orders were received. In the first quarter of 2018, the North American semiconductor equipment industrys book-to-bill ratio was 1.14, down from 1.27 in the first quarter of 2017. The most recent low occurred in October 2016 when it reached .91. What is this ratio intended to measure? Why do you think it is so closely followed?