A considerable number of 'field indicators' or 'quality indicators' have been proposed in connection with sound power determination based on measurement of intensity. For example, the ISO 9614-1 standard prescribes the use four indicators, and in the North American ANSI S12.12 standard no less than twenty-six (optional) indicators are described. Some of the quantities that have been proposed are related in an obvious manner to certain sources of error and are of obvious utility, others are only vaguely related to measurement accuracy, but might help an experienced experimenter to understand the nature of the sound field, and still others have no obvious meaning. The usefulness of a number of indicators is discussed, and possible physical interpretations are given.