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 January 2009, the North American semiconductor equipment industry’s book-to-bill ratio was 0.48, with orders of $285.6 million and billings of $579.1 million. The most recent peak in the book-to-bill ratio was in December 2003 when it reached 1.23. Orders for January 2009 declined 54 percent from the January 2008 level of $1.28 billion. What is this ratio intended to measure? Why do you think it is so closely followed?