Table 2.

Inter-Hospital Variation in Caesarean Section According to Use of Diagnostic Technology: Analyses at the Level of Each Delivery, Estimates of Hospital Random Effects with Confidence Intervals (CI), Intraclass Correlation Coefficients (ICC), and Hospital Percentiles for the Probability for Having a Caesarean Section

		Main Analyses				Additional Analyses: Placebo Test*
Variable	Year (n)	Hospital Variance Estimate for the Log Odds of Having a Caesarean Section	95% CI for the Hospital Variance Estimate	ICC	Lower (2.5%) and Upper (97.5%) Hospital Percentiles for the Probability of Having a Caesarean Section†	Hospital Variance for the Log Odds of Having a Caesarean Section	95% CI for the Hospital Variance Estimate
	I	II	III	IV	V	VI	VII
Number of types of diagnostic technology (DT1)	1967–2005 (1,708,681)
0		0.61	[0.32, 0.90]	0.16	(0.02, 0.34)	0.15	[0.04, 0.26]
1		0.18	[0.08, 0.28]	0.05	(0.05, 0.20)	0.15	[0.03, 0.27]
2		0.04	[0.02, 0.06]	0.01	(0.07, 0.14)	0.03	[0.01, 0.05]
3		0.03	[0.01, 0.05]	0.01	(0.07, 0.13)	0.02	[0.01, 0.03]
4		0.06	[0.01, 0.11]	0.02	(0.06, 0.15)	0.02	[0.00, 0.04]
Types of diagnostic technology (DT2)	1967–1985 (704,127)
No technology		0.58	[0.30, 0.86]	0.14	(0.01, 0.23)	0.11	[0.02, 0.20]
Ultrasound		0.22	[0.00, 0.44]	0.11	(0.03, 0.14)	0.11	[0.01, 0.21]
Cardiotocography		0.16	[0.05, 0.27]	0.05	(0.03, 0.13)	0.11	[−0.08, 0.30]
Ultrasound and cardiotocography		0.07	[0.03, 0.11]	0.02	(0.04, 0.10)	0.06	[0.02, 0.10]

^*The analyses were done by setting the time for getting the new technology 5 years before the hospital actually got it.

^†Calculations assume a mean probability equal to the overall rate for 1967–2005 for DT1 (=0.10) and the overall rate for 1967–1985 for DT2 (=0.06).