- term time horizon, and, obviously, according to the type of spending concerned. however, we are struck by the disparity and fragility of estimates of the same multiplier, which can double in size, depending on the method used. this means there is a risk that everyone uses these concepts in a way that serves their political preferences : certain people advocate tax cuts while others want to increase spending. in truth, few people possess the wisdom to put these multipliers into perspective and analyse them in greater detail, instead of betting time and time again on – supposedly self - financing – fiscal stimulus measures. page 11 of 19 how to define “ future expenditure ” more broadly, it is still difficult today to formally calculate productive or " future " expenditure, i. e. spending that would have the most favourable long - term effects on economic growth and output capacity or on the climate transition. a consensus appears to be emerging in economic research literature whereby spending on public investment has a more positive effect on growth than operating expenditure. for example, according to our internal models, mediumand short - term multipliers are higher for public investment than for public sector wages. but would this also be true in respect of expenditure on any roundabout or multimedia centre? there is fierce debate around what exactly investment or productive capital actually includes : “ basic ” infrastructure like roads, bridges and airports generally form the common denominator, to which building construction is sometimes added. “ social ” infrastructure such as education or public health page 12 of 19 facilities constitute another potential category of productive expenditure : investment in education and skills boosts labour productivity and the economy's innovation capacity. more recently, “ digital ” infrastructure has sometimes been included in productive expenditure, albeit with less clearly defined boundaries, and before us the enormous challenge of artificial intelligence. this list of questions without answers may appear frustrating. but it is also, primarily, a call for more research, and paris should be a centre of excellence here thanks to institutions that are pioneers in this area ( france strategie, oecd in the international arena, etc. ). as with other areas of economic policy, research in this field can help drive the action which i want to speak about next. iii. and yet, it is still possible to transform public services the key issue with operating expenditure neither our strategic review of the past few decades nor economic research offers much hope for progress. this leaves one way forward, namely practitioners and their commitment on the ground

since clarified and qualified the analysis in " economie du bien commun, iv where he called for the creation of " real public service bosses ", and for them to be afforded " considerable managerial freedom accompanied by strict ex - post evaluation ". npm gave rise to performance incentives based on indicators and assessments. the outcome of these measures would appear to be useful without being decisive, and the illusion of npm has gradually dissipated. in particular, measuring the performance and quality of certain public services sometimes runs into intrinsic measurement difficulties. v more than twenty years on from this research, twelve years after philippe aghion and alexandra roulet called for a " rethinking of central government ”, vi it is page 9 of 19 regrettable that macroeconomic analysis is still of so little assistance to public management. research literature focuses almost exclusively on assessing the success of fiscal adjustment strategies, omitting the fundamental aspects of the quality and effectiveness of public spending. certain questions have barely even been tackled. i would like to mention three, beginning with measurement of the output of public services. how to measure the output of public services? the inherent lack of a selling price for non - market public service output has never really been overcome, and national accounting uses a simplistic arrangement to get around this, consisting of measuring it as the sum of production costs vii - in other words, mainly public employee remuneration. this basically means that the only way to increase public service output today is to increase costs and the number of public employees. but how can we gauge the effectiveness and quality of public spending and public services without having any visibility over their'real'output? the concept of the " efficiency frontier ", part of a nascent research field that is little used in france, may provide a partial answer to this question. viii it involves comparing the relationship between each type of public spending and one or more international performance indicators ( for example, the pisa scores for education ) between different countries. however, this remains a little - known, insufficiently operational concept with recurring methodological difficulties for comparing public spending between different countries. page 10 of 19 how to interpret fiscal multipliers? another area of economic research providing a greater body of work is the calculation of fiscal multipliers. the effect of a fiscal measure on the economy varies depending on the channel used ( public expenditure or tax ), how it is financed ( whether debt is used or not ), whether there is a short - or medium