that productivity growth has been mildly positive for aggregate employment. their 3 / 16 bis central bankers'speeches country - industry panel regressions suggest that – over long periods of time – the negative effect of productivity growth on employment in the same industry is more than compensated by positive “ spillovers ” in terms of expansions in other industries. thus, structural change triggered by technical progress, ultimately, creates more employment in new sectors than it destroys in old ones. does this pattern change over time? figure 2, taken from autor and salomons ’ ( 2017 ) sintra paper, compares the estimated own ( “ internal ” ) industry effects, the external effects on ( or spillovers to ) other industries and the net effects for four different decades. in line with the pooled results, the internal effects are consistently negative and the external effects consistently positive. in the 2000s, however, the positive external effects are so small that the net effects turn negative. whether this means a reversal of the historical pattern is open to debate. the authors indicate that as early as in the 1980s negative and positive effects were basically cancelling each other out but strong positive spillovers returned in the 1990s. moreover, preliminary follow - up work with a different database going up until 2014 seems to suggest that another recovery of the benign productivity - employment relationship may have emerged ( though these results could be subject to change ). ultimately, only the future will tell. indeed, another online survey showed that participants of the sintra forum were divided on this issue. 43 % of voters indicated that technological innovation will have an insignificant impact on employment in the next 10 years. 28 % felt that the net impact would be positive and an equal share that it would be negative. 4 / 16 bis central bankers'speeches interestingly, the historical productivity - employment nexus is quite different across sectors. for example, the strongest positive employment spillovers originate from productivity growth in lowtech services ( capturing e. g. car sales, real estate, hotels and catering or social and personal services ). significantly positive spillovers also emerge from high - tech services ( e. g. telecommunication and financial intermediation ) as well as health and education. autor and salomons do not find significant external effects of other sectors. more worrying, however, are their results on the effects of productivity growth on the composition of labour demand. they find clear evidence of “ polarisation ” in the group of 19 advanced economies in that most new jobs were – on average –

– according to hal varian ( 2017 ) – and quantum computing is on the way. so, mokyr does not see why the growth in economic welfare should slow down for technological reasons. in this context, it was interesting that an online poll showed that 72 % of voting sintra participants felt that the productivity gains from the ict ( information and communication technology ) revolution will 2 / 16 bis central bankers'speeches accelerate, given that its full potential has not emerged yet. reinhilde veugelers ( 2017 ) added that it is diffusion that makes innovation such a powerful growth engine. she referred to recent evidence produced by the oecd suggesting that the diffusion and adoption of the latest technology across firms may be more of a problem than a lack of innovation as such ( andrews et al. 2015 ). ( this point had already been much emphasised by mario draghi and catherine mann at the 2015 ecb sintra forum ; see constancio et al. 2015. ) she reckoned that the most potent mechanism for the transfer of new know - how is when the innovating researchers move from frontier firms to other sectors or firms. in addition to mokyr, several other speakers also considered measurement problems affecting productivity assessments, e. g. through the underestimation of gdp ( the numerator of aggregate productivity measures ). jones ( 2017 ) and varian ( 2017 ) referred to software or services provided for free or at very low prices by ict firms or not - for - profit institutions ( e. g., facebook, google or wikipedia ). the problems are particularly pronounced in areas involving rapid quality change, such as photography, the global positioning system ( gps ) or, more generally, the smartphones in which these and many other applications are embedded. at zero or near - zero prices, hedonic quality adjustments in nominal national accounts are difficult. recent literature, such as byrne et al. ( 2016 ) or syverson ( 2017 ), however, argues that the “ free ” services and other ict features only account for a small part of the productivity slowdown in the us. based on the practice of statistical agencies to impute value developments of disappearing products from value developments of surviving products, philippe aghion presented in sintra sizeable growth underestimation for france and the us, amounting to slightly more than half a percentage point of measured annual growth ( see aghion et al. 2017b for the us ). but jones