Ghost note (of Motown), Rocco Prestia (for Tower of Power), and Chuck Rainey (for Steely Dan, Aretha Franklin, and others) all include "tons of ghost notes done right" in their playing. In vocal music, especially in musical theater, a ghost note represents that the lyrics must be spoken rather than sung, retaining the marked rhythm but having indeterminate pitch. Notes with value less than a half note use an "X" instead of an oval as a note head. Occasionally a half note or whole note is represented with an open diamond note head, often representing a scream or grunt. As an extreme
Value of time can be examined. For example, if a traveler has a choice between a coach which takes six hours and costs £10, or a train which takes four hours and costs £30, we can deduce that if the traveler chooses the train, their value of time is £10 per hour or more (because they are willing to spend "at least" £20 to save two hours' travel time). The difficulty in narrowing down the "actual" value of time from a pair of choices means that hypothetical situations are generally used (the stated preference technique) to deduce values of time. The value of