Table 4. 95% limits of reliability and 95% confidence interval by age-group.

The low correlations obtained for the 4-year-olds are correct; they are partly because only one child in this age-group scored 1600 arcsec on either test (and this child then scored 40 arcsec on retest), so there was a lower range of values (note the high confidence intervals).

Age-group	N children	95% limits of reliability and 95% confidence interval on these		Correlation coefficients
		In log10 arcsec	As a factor	Spearman	Pearson
3 year olds	20	0.71 (0.42 to 1.01)	5.15 (2.61 to 10.13)	0.47 (0.036–0.76)	0.72 (0.4–0.88)
4 year olds	47	0.82 (0.60 to 1.03)	6.54 (4.02 to 10.65)	0.13 (-0.17–0.4)	0.045 (-0.25–0.33)
5 year olds	27	0.64 (0.42 to 0.87)	4.38 (2.61 to 7.35)	0.79 (0.58–0.9)	0.59 (0.28–0.79)
6 & 7 year olds	48	0.56 (0.42 to 0.70)	3.63 (2.61 to 5.06)	0.65 (0.46–0.79)	0.72 (0.54–0.83)
10 & 11 year olds	40	0.28 (0.20 to 0.36)	1.91 (1.59 to 2.30)	0.47 (0.19–0.68)	0.86 (0.74–0.92)
All	182	0.63 (0.55 to 0.71)	4.27 (3.54 to 5.15)	0.59 (0.49–0.68)	0.62 (0.52–0.7)