Table A2.

A summed score conversion table for the proposed IPSyn-C in yearly intervals for ages 2–6 years (see Table A1).

Summed			Percentile rank						Summed			Percentile rank
Score	T score	SE	24–72 mos.	24 mos.	36 mos.	48 mos.	60 mos.	72 mos.	Score	T score	SE	24–72 mos.	24 mos.	36 mos.	48 mos.	60 mos.	72 mos.
0	14.8	4.3	0	0	0	0	0	0	43	54.1	2.7	66	100	73	33	7	1
1	17.0	4.2	0	0	0	0	0	0	44	54.8	2.7	68	100	77	38	9	1
2	18.7	4.1	0	0	0	0	0	0	45	55.5	2.7	71	100	80	43	11	1
3	20.3	3.9	0	0	0	0	0	0	46	56.2	2.7	73	100	84	48	14	2
4	21.8	3.7	0	0	0	0	0	0	47	56.9	2.7	75	100	86	52	16	2
5	23.1	3.5	0	1	0	0	0	0	48	57.7	2.7	78	100	89	58	20	3
6	24.3	3.4	1	1	0	0	0	0	49	58.4	2.7	80	100	91	63	24	4
7	25.5	3.3	1	2	0	0	0	0	50	59.1	2.7	82	100	93	67	28	5
8	26.6	3.2	1	3	0	0	0	0	51	59.8	2.8	84	100	95	71	32	6
9	27.6	3.1	1	5	0	0	0	0	52	60.6	2.8	86	100	96	76	37	8
10	28.6	3.1	2	7	0	0	0	0	53	61.3	2.8	87	100	97	79	41	10
11	29.5	3.0	2	9	0	0	0	0	54	62.1	2.9	89	100	98	83	47	13
12	30.4	3.0	2	12	0	0	0	0	55	62.8	2.9	90	100	98	86	52	16
13	31.3	2.9	3	15	0	0	0	0	56	63.6	3.0	91	100	99	89	57	20
14	32.2	2.9	4	19	0	0	0	0	57	64.4	3.0	93	100	99	91	63	24
15	33.0	2.9	4	23	0	0	0	0	58	65.3	3.1	94	100	99	94	68	29
16	33.8	2.8	5	28	0	0	0	0	59	66.1	3.1	95	100	100	95	73	34
17	34.6	2.8	6	32	0	0	0	0	60	67.0	3.2	96	100	100	96	78	40
18	35.4	2.8	7	37	0	0	0	0	61	67.9	3.3	96	100	100	98	82	46
19	36.2	2.8	8	43	1	0	0	0	62	68.8	3.4	97	100	100	98	86	52
20	37.0	2.8	10	48	1	0	0	0	63	69.7	3.5	98	100	100	99	89	58
21	37.8	2.8	11	54	1	0	0	0	64	70.7	3.6	98	100	100	99	92	65
22	38.5	2.8	13	59	2	0	0	0	65	71.7	3.7	98	100	100	100	94	71
23	39.3	2.8	14	64	3	0	0	0	66	72.8	3.8	99	100	100	100	96	77
24	40.1	2.8	16	68	3	0	0	0	67	73.8	3.9	99	100	100	100	97	82
25	40.8	2.8	18	73	5	0	0	0	68	75.0	4.0	99	100	100	100	98	87
26	41.6	2.8	20	78	6	0	0	0	69	76.1	4.1	100	100	100	100	99	91
27	42.3	2.8	22	81	8	1	0	0	70	77.3	4.2	100	100	100	100	99	94
28	43.1	2.8	25	85	10	1	0	0	71	78.6	4.3	100	100	100	100	100	96
29	43.9	2.8	27	87	12	1	0	0	72	79.8	4.5	100	100	100	100	100	97
30	44.6	2.8	29	90	15	2	0	0	73	81.1	4.6	100	100	100	100	100	99
31	45.4	2.8	32	92	18	3	0	0	74	82.4	4.7	100	100	100	100	100	99
32	46.1	2.8	35	94	22	3	0	0	75	83.7	4.8	100	100	100	100	100	100
33	46.8	2.8	37	95	26	5	0	0	76	84.9	4.9	100	100	100	100	100	100
34	47.6	2.8	41	96	30	6	0	0	77	86.1	5.0	100	100	100	100	100	100
35	48.3	2.8	43	97	35	8	1	0	78	87.3	5.1	100	100	100	100	100	100
36	49.1	2.8	46	98	39	9	1	0	79	88.3	5.2	100	100	100	100	100	100
37	49.8	2.8	49	99	45	12	1	0	80	89.3	5.2	100	100	100	100	100	100
38	50.5	2.8	52	99	50	15	2	0	81	90.3	5.3	100	100	100	100	100	100
39	51.2	2.8	55	99	54	18	2	0	82	91.2	5.4	100	100	100	100	100	100
40	52.0	2.7	58	99	60	21	3	0	83	92.1	5.5	100	100	100	100	100	100
41	52.7	2.7	61	100	64	25	4	0	84	92.9	5.6	100	100	100	100	100	100
42	53.4	2.7	63	100	69	29	6	0	85	93.7	5.6	100	100	100	100	100	100
									86	94.4	5.7	100	100	100	100	100	100

Note. The T score is a standardized score with a mean of 50 and an SD of 10 that is transformed from item response theory scaled scores. If a child received a summed score of 20 (see the bold number line in the table), the corresponding T score is 37.0, and the standard error of the T score is 2.8, which means the 95% confidence interval for the child's score would be [37 – 1.96 × 2.8, 37 + 1.96 × 2.8]. With respect to the population of typically developing children between 24 and 72 months of age, this child's score is at the 10th percentile. If the child is 24 months old, the percentile rank is 48. If this child is 36 months old, the score falls at the first percentile, and the child can be flagged as a late talker with only 2% of likely error. The bold and underlined scores in the 36th and 48th month columns indicate that the children with those scores are highly likely to be late talkers with only 2% false positive rate. If a score is bold, the child can be flagged as atypical with 80% correct probability, but also with a larger probability (40%–50%) of false diagnosis. mos. = months.