Speech improvement depends on a thorough understanding of the individual. A diagnostic program is the key for this insight. This point of view was summarized by Doctor Harry G. Barnes, who states that group tendencies exist, varying according to local and community conditions, and that by basing general teaching procedures upon these indications one may help to bring instruction to the level of the students, but: "The range and peculiar nature of individual differences within the group indicates that teaching must be made specific to individual needs and abilities, if the training is to be efficient, economical, progressive. Therefore, a serviceable, reliable, valid, diagnostic technique is the first and most important requirement of those who would improve the speech habits of their pupils."
