Table 5 Estimated cost impact of gatekeeping plan membership compared with fee for service plan membership (based on two part models).

	Number*	Cost difference (fee for service minus gatekeeping) in persons with non‐zero costs‡	Number†	Cost difference (fee for service minus gatekeeping) in all persons§	Cost difference (fee for service minus gatekeeping) in all persons (%)§¶
Total costs
Reduced model	372	498 (−77 to 1072)	439	403 (−120 to 1027)	14.5
Extended model	347	513 (53 to 973)	395	517 (−11 to 1254)	18.9
Outpatient costs
Reduced model	377	544 (76 to 1014)	444	453 (28 to 973)	24.6
Extended model	354	394 (23 to 765)	402	372 (−4 to 813)	17.9

*Number available for GLM fitting. Reduced and extended total cost models, three gatekeeping observations and four fee for service observations with health care costs over Sw fr20000 in 2000 not used. Reduced outpatient cost model, one fee for service observation with outpatient costs over Sw fr20000 in 2000 not used. In the extended outpatient cost model, this observation was not contained because of a missing value in one of the additional predictor variables. †Number available for estimation of marginal (population) effects. ‡Conditional effect in persons with non‐zero costs as derived from GLM coefficients. Mean Sw fr per person (CI). §Marginal (population) effect (combined effect estimate of two part regression, comparing the assumptions of exclusive gatekeeping plan membership and with exclusive fee for service plan membership). Mean Sw fr per person (bootstrapped CI). ¶Expressed as a percentage of the costs incurred by the fee for service source population in the year of reference.