Table 4. Model-based mean and SEM of test-retest level shifts given by f2 and retest interval provided for a variety of ages.

Results are adjusted for correlations among multiple DPOAE measures in each participant and for child-specific variation in level. Thus they are expected to be more accurate than raw data presented in Table 2. These results can be used to generate shift reference intervals using calculations provided in the Introduction. Once validated using locally-developed norms, the associated reference intervals could be used to inform clinical testing.

		Follow-up Interval (in months)
		2			4
		MeanShift	MeanSEM	SESEM	MeanShift	MeanSEM	SESEM
f2 Primary (Hz)	Baseline Age (in months)
2063	4	−0.7	3.2	0.3	−1.3	3.2	0.2
	24	−0.1	3.3	0.2	−0.1	3.3	0.2
	48	−0.1	3.7	0.3	−0.1	3.7	0.3
	96	−0.1	2.9	0.3	−0.3	2.9	0.3
3000	4	−0.7	2.7	0.2	−1.3	2.7	0.2
	24	−0.1	2.9	0.2	−0.3	2.9	0.2
	48	−0.1	3.0	0.2	−0.2	3.0	0.2
	96	−0.1	2.7	0.3	−0.3	2.7	0.3
4219	4	−0.8	3.5	0.3	−1.4	3.6	0.3
	24	−0.1	3.5	0.2	−0.1	3.4	0.2
	48	−0.1	2.9	0.2	−0.1	2.9	0.2
	96	−0.1	2.8	0.3	−0.3	2.8	0.3
6000	4	−0.4	3.6	0.3	−0.7	3.5	0.3
	24	0.0	2.9	0.2	0.0	2.9	0.2
	48	−0.1	3.0	0.2	−0.1	3.0	0.2
	96	−0.2	3.0	0.3	−0.3	3.0	0.3