A short-form version of the Australian English Communicative Development Inventory

Figures & data

Table I. Distribution of items according to semantic categories.

Semantic category	n OZI	% OZI	% OZI-SF	n OZI-SF
Sounds	12	2.15	2.04	3
Animals	42	7.53	7.15	7
Vehicles	14	2.51	2.38	2
Toys	17	3.05	2.89	3
Food/Drink	63	11.29	10.73	11
Clothing	24	4.30	4.09	4
Body parts	27	4.84	4.60	5
Small items	49	8.78	8.34	8
Furniture	30	5.38	5.11	5
Outside	32	5.73	5.45	6
Places to go	21	3.76	3.58	4
People	29	5.20	4.94	5
Games/Routines	24	4.30	4.09	4
Action words	108	19.35	18.39	17
Descriptive words	66	11.83	11.24	11
	558	100.00	95.02	95

Table II. Distribution of items according to Age of Acquisition.

Age (months)	n OZI	% OZI	% OZI-SF	n OZI-SF
13	3	0.54	0.51	1
14	1	0.18	0.17	1
15	1	0.18	0.17	1
16	7	1.26	1.19	1
17	9	1.62	1.54	3
18	14	2.51	2.39	2
19	25	4.49	4.26	4
20	18	3.23	3.07	3
21	14	2.51	2.39	2
22	91	16.34	15.52	16
23	37	6.64	6.31	6
24	26	4.67	4.43	4
25	35	6.28	5.97	6
26	79	14.18	13.47	13
27	80	14.36	13.64	13
28	8	1.44	1.36	1
29	20	3.59	3.41	3
30	15	2.69	2.56	3
31	74	13.29	12.62	12
	557*	100.00	95.00	95

*This sums to 557 (not 558) because the item “own name” is not included in AoA data.

Table III. OZI-SF items with Age of Acquisition (months) from the OZI long-form norms.

Baa Baa	17	Hat	19	Tree	22	Pull	26
Uh oh	15	Necklace	28	Pool	22	Shake	27
Ouch	19	Shoe	17	Flag	29	Run	22
Kangaroo	23	Coat	29	Shop	22	Think	30
Bird	17	Lips	26	House/home	22	Wish	30+
Cat	18	Toes	21	Beach	25	Look	23
Bear	22	Leg	22	School	24	Big	23
Sheep	22	Chin	22	Mummy	13	Gentle	26
Spider	22	Tongue	24	Grandma/nanna	14	Careful	26
Penguin	26	Glass	27	Person	30+	Dirty	22
Airplane	19	Clock	22	Friend	27	Fine	30+
Boat	20	Mop	30+	Doctor	26	Mad	30+
Game	27	Comb	27	Lunch	25	Noisy	30+
Puzzle	25	Towel	23	Call	25	Slow	30
Present	25	Glass	27	Thank you	18	Happy	26
Pasta	25	Keys	19	Night-night	21	Tiny	30+
Beans	27	Picture	26	Carry	26	Drop	26
Meat	27	Chair	20	Chase	27	Build	27
Peas	24	Bed	20	Dump	30+	Black	26
Salt	30+	Oven	27	Finish	24	No	16
Yoghurt	22	Stairs	23	Fit	27	*Today
Cereal	27	Bench	30+	Hug	22	*She/he
Custard	30	Cloud	26	Listen	29	*Does
Carrot	23	Swing	22	Like	26	*Down
Pudding	30+	Sun	22	Pretend	30+	*In

The order of items in Table III reflects CDI semantic categories.

*Indicates the five added items on time, pronouns, prepositions, and question words that were not in the OZI long-form inventory (hence they lack OZI age norms).

Table IV. Correlations between OZI and OZI-SF scores for subsamples.

Subsample	Correlation	Correlation after age partialed out
Simulation 1: aged 12–18 months	r(20) = 0.945, p < 0.001	r(20) = 0.914, p < 0.001
Simulation 1: aged 20–24 months	r(15) = 0.987, p < 0.001	r(15) = 0.988, p < 0.001
Simulation 1: aged 26–30 months	r(15) = 0.990, p < 0.001	r(15) = 0.988, p < 0.001
Simulation 2: 10^th percentile	r(20) = 0.980, p < 0.001	r(20) = 0.865, p < 0.001
Simulation 2: 50^th percentile	r(19) = 0.996, p < 0.001	r(19) = 0.996, p < 0.001
Simulation 2: 90^th percentile	r(19) = 0.995, p < 0.001	r(19) = 0.899, p < 0.001

Figure 1. Correlations between OZI scores and simulated OZI-SF scores, for the OZI norming sample.

Figure 2. Screenshot of the online OZI-SF interface showing response choices and supporting images.

Table VI. Gesture development by age.

Age used	Gesture
12 months	Extending the arms to show the caregiver the child is holding something
	Extending the arm upward to signal a wish to be picked up
	Reaching out to give the caregiver a toy or some object that the child has
	Pointing with the arm and index finger at some interesting object or event
18 months	Blowing kisses from a distance
	Shrugging to indicate “all gone” or “where’d it go?”
	Gesturing “hush” by placing the finger to lips
	Nodding the head “yes”

Figure 3. (A) Receptive scores by percentiles (10^th, 25^th, 50^th, 75^th, and 90^th), on OZI-SF (independent norming sample). (B) Expressive scores by percentiles (10^th, 25^th, 50^th, 75^th, and 90^th), on OZI-SF (independent norming sample).

Table V. Descriptive statistics for child age by sex within each age group.

Age group (months)	Sex	Mean age	Standard deviation	Standard error	n
10.5–13.4	F	11.70	0.85	0.19	19
	M	11.76	0.91	0.20	21
13.5–16.4	F	14.97	0.98	0.33	9
	M	14.76	0.87	0.26	11
16.5–19.4	F	18.07	0.85	0.22	15
	M	18.14	0.87	0.21	17
19.5–22.4	F	21.10	0.69	0.18	15
	M	21.12	0.83	0.02	17
22.5–25.4	F	23.63	0.73	0.19	15
	M	23.90	0.80	0.17	23
25.5–28.4	F	26.83	0.85	0.20	18
	M	27.18	0.87	0.22	16
28.5–31.4	F	29.73	0.75	0.16	20
	M	29.97	0.57	0.17	12