委托代理模型与供给诱导需求(编辑修改稿)

委托代理模型与供给诱导需求(编辑修改稿)内容摘要：

of reputation. Difficult to know exactly how far D curve can be induced to shift – depends upon relationship between costs of inducement and incremental earnings of doctor. Target Ine Model If doctors have a “target ine” then any reduction in price caused by higher supply of doctors will be offset by inducing extra demand. Problem with this explanation is that it does not say what target ine should be – if doctors can manipulate demand then why do they not exploit this so as to immediately obtain profit maximising ine as opposed to waiting for increased S. These shortings led to next model. Disutility of Discretion Model This model makes the level of inducement endogenous – thus both equilibrium inducement level and ine level are determined within the model. Suppose doctor’s utility function is given by ),( DWYUU  where Y is ine, W is hours of work and D is discretionary influence used to augment demand. We assume increasing marginal disutility of augmenting demand – doctors do not enjoy trying to induce demand and there are greater incremental losses of utility with greater inducement – must be balanced against marginal utility of ine arising from such demand. Thus demand is augmented to where these are equal also allowing for marginal disutility of added work. Can be represented graphically, where we hold W constant for simplicity. Thus utility depends upon Y and D. Indifference curves here represent doctor’s preferences – they are upward sloping because D is a “bad”. Suppose for convenience that D is measured in units representing number of induced units of service – if sold at constant rate of profit π0 and if maximum profit level with zero inducement is π0Q0 then doctor’s total ine is Y=π0Q0+πD. This is a linear equation with intercept of π0Q0 and slope of π0. If doctor locates at highest level of utility this is point A. Now suppose there is an increase in number of doctors which leads to reduction in vaerge profit rate received for services from π0 to π1. This gives budget constraint with lower slope and intercept and doctor locates at point B. Thus doctor has chosen higher level of inducement DBDA. However, the model is ambiguous in terms of effect of increased number of doctors on inducement. Y YA YB Π0Q0 Π1Q1 Π0Q0+π0D Π1Q1+π1D D DA DB B A B* Depending upon preferences, doctor could easily locate at point B*, thus giving lower level of inducement. Evidence on SID We now review some evidence. If imperfect agency between doctor and patient exists then we should see those with more plete information consume less services. Thus controlling for other factors medical professionals and their families should consume fewer health services – this is not the case, though it may be that costs of consuming medical services for these families is lower. Studies have also tried to distinguish between patientinitiated visits and doctorinitiated visits. SID would suggest that following increase in number of doctors, then doctor initiated visits should increase, but patient initiated ones should not. Some evidence of this but effect is small – also patient initiated visits may be influenced by travel, waiting costs etc. If these fall following rise in number of doctors then patientinitiated visits will also respond to increase in number of doctors. Evidence for Ireland Tussing (1983 and 1985, see library catalogue entry for A. Dale Tussing) looked at this for Ireland he asked patients attending GPs whether the present consultation was their’s or the GP’s idea and whether the visit led to a future return visit being rearranged. Found that such return visits were correlated with GP density in the direction predicted by SID (. where there was higher GP density more inducement was seen). Also found that such return visits were lower where there was a higher proportion of patients with free GP care. Concluded that since GP utilisation is higher amongst such patients there is less need for pensatory induced demand. Madden, Nolan and Nolan (2020) looked at how GPs responded to change in financial incentives facing them. See Suppose that GPs face two types of patients, GMS or medical card patients and “private” patients. Also assume that initially the reimbursement system is feeforservice, but in the case of GMS patients this fee is paid by the state. Also assume that the initial visit of a patient to a GP is determined by the patient – GPs can only influence (induce) subsequent visits. We assume a very simple utility function for doctors – effectively it is their gross revenue less the cost of effort (of carrying out a cons。