Table 1.

Sample means and standard deviations of descriptive variables for the 10 selected participants.

Variable	M	SD
Proportion of utterance attempts comprehensible a	0.61	0.17
Arizona Articulation Proficiency Scale standard score b	68	7.70
Mean length of utterance a	1.60	0.49
Number of different word roots c	79	45
IQ d	82	18
Receptive vocabulary standard score e	55	20
Chronological age in years at period for current study	13	1.60

^a Average score over two 20-min conversational speech samples with an unfamiliar research staff at the current study's measurement period.

^b Arizona Articulation Proficiency Test–Third Edition (Fudala, 2000) at 9 months prior to period for current study; population M (SD) is 100 (15).

^c Average of scores over two 20-min conversational speech samples at the current study's measurement period.

^d Stanford Binet–Fourth Edition (Thorndike, Haden, & Sattler, 1986) at 9 months prior to period for current study; population M (SD) is 100 (15).

^e Peabody Picture Vocabulary Test–Fourth Edition (Dunn & Dunn, 2007) at 9 months prior to period for current study; population M (SD) is 100 (15).