. 1996 Summer;17(4):23–42.

Table 4. Multivariate Analysis of Ambulatory Service Use.

Independent Variables	Dependent Variables

	Total Visits	Visits to Other Providers	Laboratory Services	Imaging Services

	Average of All Patients for Each Practice
Intercept	^***9.55	^**2.79	-0.77	^*2.79
PCS Specialty¹
Internal Medicine, Solo	^***0.54	^***0.57	^***2.03	^***0.57
General or Family Practice, Group	^**-0.31	-0.04	-0.05	0.67
Internal Medicine, Group	^***0.70	^***0.89	^***3.77	^***1.02
Multispecialty Group	0.04	^***0.74	^***1.41	^***0.78
Primary-Care Group	^*0.30	^*0.19	0.58	0.16
Metropolitan Region²	^**-0.17	^***0.23	^**0.57	-0.04
PCS Practice Size³
Above 70th Percentile	^***-0.26	^***-0.24	^***-0.97	^***-0.19
Below 30th Percentile	^***0.26	^***0.42	^*0.45	0.09
PCS Practice Mean Age	^***-0.13	^***-0.05	-0.12	^*-0.03
PCS Female Caseload³
Above 70th Percentile	0.08	0.01	0.28	0.03
Below 30th Percentile	-0.06	^***0.19	-0.12	^**0.13
PCS Practice Mean Number of Comorbidities per Patient	^***1.33	^***0.52	^***3.58	^***0.44
State of Practice⁴
Alabama	^***0.42	^**0.14	^***1.52	^*0.12
Maryland	^***1.47	^***0.72	0.02	-0.10
Adjusted R²	0.42	0.40	0.33	0.18
Mean	7.13	2.96	9.52	2.87

p < 0.05.

^**

p < 0.01.

^***

p < 0.001.

Reference group is general or family practice, solo.

Reference group is rural.

Reference group is 30th to 70th percentile.

⁴

Reference group is Iowa.

NOTE: PCS is primary-care source. N=2,972.

SOURCE: Health Care Financing Administration, Bureau of Data Management and Strategy: Data from the National Claims History file, July 1, 1990-June 30, 1991; data analysis by Parente, S.T., Weiner, J.P., Garnick, D.W., et al., 1996.