如何糾正經濟數據與現實的偏差
It is faintly surprising that one of the liveliest areas of economics these days is the question of measurement, and what relation published statistics bear to what is happening in the economy. Statistics do not usually inspire excitement.
如何衡量經濟活動以及統計數據與實際經濟情況之間的關係最近成爲了經濟學最活躍的領域之一，這有點出人意料，統計學通常不會激起人們的興奮之情。This attention reflects the convergence of two strands of scepticism about the existing statistics, and in particular gross domestic product. One is the “productivity puzzle” and to what extent the mis-measurement of digital phenomena helps explain the slow rate of productivity growth. The other is the longstanding critique of GDP as a meaningful measure of progress, for reasons of environmental sustainability or other contributors to society’s wellbeing.
這種關注反映出對當前統計手段的兩種質疑的共同點，尤其是針對國內生產總值(GDP)的質疑。一種涉及“生產效率謎題”，以及對數字經濟的不當衡量在多大程度上有助於解釋生產率增長緩慢。另一種是長期以來對GDP作爲進步衡量指標的合理性的批評，理由是GDP未能考慮環境可持續性或者其他促進社會福祉的因素。The two converge on the distinction between the aggregate amount of marketed economic activity and total economic welfare. The conventional statement about GDP is that it is only meant to count the former, not the latter. GDP does not capture environmental factors or consider income distribution. But as long as that gap has been roughly constant, GDP growth has been a good enough measure of improvement in economic welfare.
這兩種懷疑都着眼於市場經濟活動總量(marketed economic activity)和總經濟福祉(total economic welfare)之間的區別。關於GDP，傳統的說法是GDP只是爲了衡量前者，而非後者。GDP並不把環境因素或者收入分配納入考慮。但只要兩者差距大致保持穩定，GDP增長率足以作爲衡量經濟福祉改善程度的良好指標。
Perhaps the wedge between total marketed economic activity and welfare is increasing because of the pace of technological change, but statistics have never captured the human gains from advances in periods of innovation, whether in medicines or the internet.
市場經濟活動總量和總經濟福祉之間的差距或許正因爲技術變革而擴大，但統計從未考慮藥物或者互聯網等創新給人類帶來的福祉。This case for the defence of GDP is fundamentally weak, however. It in fact includes many non-marketed activities, yet excludes other productive activity. Business and government count as “the economy” but voluntary and household activities do not.
然而，這個爲GDP辯護的理由根本站不住腳。GDP實際上涵蓋了許多非市場的活動，卻把其他一些生產活動排除在外。企業和政府都算作“經濟”，但志願勞動和家務勞動卻不算在內。Postwar social changes — a rising proportion of women working outside the home, and the increased purchases of prepared foods, professional childcare, domestic appliances and so on — have flattered the official productivity statistics for decades.
數十年來，戰後的種種社會變化——走出家門工作的女性的比例上升，人們購買更多的預製食品、專業的兒童保育服務、家用電器等產品和服務——使官方的生產率數據被高估。More subtly, the statistics blur the distinction between marketed economic activity and increases in economic welfare that cannot be priced by converting nominal GDP into “real” terms.
更微妙的是，通過把名義GDP轉換爲“實際”GDP，統計模糊了市場經濟活動和無法定價的經濟福祉增長之間的差異。Economists and statisticians are beginning to accept that our framework for economic statistics needs to change. Some argue for developing better “satellite” accounts, where all the interesting data about the environment or the household are collated.
經濟學家和統計學家開始接受，我們的經濟統計框架需要改革。一些人主張設立更好的“衛星賬戶”，將一切有關環境或者家庭的有趣數據歸入這個賬戶。But why should all the pressing questions be satellites?
但爲什麼這些迫切的問題要居於附屬地位呢？GDP could certainly be improved. In one of the joint winners of the Indigo Prize essay competition, a team led by Carol Corrado and Jonathan Haskel, proposed better measurement of services and intangibles, and direct measurement of the economic welfare being created by digital goods. The other winning essay — which I co-authored with Benjamin Mitra-Kahn — proposed similar incremental changes as an interim step.
我們當然能夠改進GDP。經濟學獎Indigo Prize徵文比賽的獲獎者之一、由卡蘿爾?科拉多(Carol Corrado)喬納森?哈斯克爾(Jonathan Haskel)領導的小組，提出了更好地衡量服務和無形資產的方法，以及直接衡量數字產品創造的經濟福祉的方法。另外一篇獲獎文章——由我與本傑明?米特拉-卡恩(Benjamin Mitra-Kahn)合作撰寫——提出了類似的漸進變革作爲一種臨時措施。We opted for better measurement of intangibles, adjusting for the distribution of income, and removing unproductive financial activity. The long-term recommendation was more radical: ditching GDP as the metric of progress in favour of measures of access to different kinds of assets, including financial wealth but also natural capital, intangible assets, infrastructure and human and social capital.
我們主張更好地衡量無形資產、根據收入分配進行調整，以及去除非生產性金融活動。針對長期的建議則更加激進：摒棄GDP作爲衡量進步的指標，轉而衡量人們獲得和使用各類資產的機會，這些資產不僅包括金融財富，也包括自然資本、無形資產、基礎設施、人力和社會資本。
This was inspired by Amartya Sen’s idea that prosperity consists in people having the capabilities needed to lead the life they would find meaningful; and by the need to get away from measuring economic progress only through the short-term flow of activity. There is no sustainability without a balance sheet.
這受到了兩方面的啓發，一是阿瑪蒂亞?森(Amartya Sen)的觀點，他認爲繁榮的意義在於人們擁有過上自己認爲有意義的生活所需要的能力；第二是我們有必要摒棄只通過短期活動情況來衡量經濟進步的做法。沒有一個“資產負債表”，就談不上什麼可持續性。Perhaps neither the incremental nor the radical is the right approach. Reform will take time because there needs to be consensus about how to change; statistical standards are like technical standards. But I am now confident that in another 10 or 20 years GDP will have been dethroned.
或許上述漸進改革和激進改革都不是正確的策略。改革需要時間，因爲需要就如何改革達成共識；統計標準就像是技術標準。但我現在確信，再過10至20年，GDP將走下神壇。
