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姚松炎

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增土地供應遏樓價?恐隔山打牛

增土地供應遏樓價?恐隔山打牛
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香港經過了三個月的土地大辯論,各界不斷激辯,主因當然是由於香港的樓價貴得驚人,已經連續八年成為世界最不能負擔的樓價。政府卻不准討論貨幣政策、按揭政策或人口政策,只准討論從那裡找尋增加土地供應的方法,政府認定增加土地供應就是壓抑樓價上升的唯一方法,卻從未科學論證;不少市民和民間組織並不認同政府的見解,有民間團體曾進行問卷調查發現,為數不少的市民不認為增加土地供應可解決樓價不能負擔的問題[1]。

澳洲去年亦曾有類似的討論 [2],他們的經濟學教授與建造業專業人士同樣出現意見分歧,建造業作為既得利益者,自然支持增加供應可壓抑樓價的理論。然而,他們的學術界有不少意見認為只增供應、不理需求對壓抑樓價無補於事,過去幾年的樓價上升正正是由於投資需求所致,譬如新南威爾士大學的房屋政策研究教授Hal Pawson有以下的見解:

"Supply is only one side of the house price story, it is important to look at demand to try to moderate spiralling house prices. He says that high levels of investment and tax incentives like negative gearing are pumping up demand." [2]

事實上,大量學術研究已經證明樓價上升與信貸供應增加有關 [3,4],因此,自從2008年的國際金融風暴,全球央行大幅減息及進行量化寬鬆,導致世界各地的房產價格上升,已非香港或澳洲本身的房產供應量所能左右。今年8月初,經濟學人分析了全球22個城市的樓價變化,過去5年只有2個城市的樓價下跌,其餘20個城市均出現不同程度的樓價上升(圖1),而香港的升幅只有39.3%,屬溫和增長率;其餘有11個城市的樓價升幅比香港為高,反映樓價上升受全球低息引致的信貸增長及資本流動所影響,並非個別城市的土地供應問題所能改變大局。

全球樓價變化不但呈現方向一致,部份城市更加出現周期相近現象,譬如澳洲雪梨與英國倫敦的樓價指數年度變化率從2006年至2018年中呈現的周期變化(圖2),雖然升跌幅度不完全相同,但周期時間異常接近。兩個城市,一個在澳洲,一個在歐洲,兩處的房屋供應及房屋需求實在不可能出現這麼相似的周期變化,其成因必然是在兩處皆出現的現象,其中最有可能是關於外來資本流入(Capital Inflow)從不同渠道推升樓價,包括外資直接購房、直接或間接的信貸供應增加(Credit Supply)及維持低息環境。(Richter and Werner, 2016 [6])

事實上,已有多份研究顯示外來直接投資或資本流入對樓價有推升影響,其中包括美國(Sa and Wieladek, 2011[9]),英國(Sa, 2017 [10])、澳洲 (Fereidouni and Tajaddini, 2016 [11]; Guest and Rohde, 2017 [12]; Wokker and Swlerings, 2016 [13]);新興經濟體(Ghollpour, 2013 [14];Tillmann, 2013 [15]);東盟、新加坡和香港(Yiu and Sahminan, 2017 [16];Chow and Xie, 2016 [17];Cheung et al., 2017 [18])。

澳洲國土廣闊,尚且無法透過增加供應來壓抑樓價,去年決定收緊非本地人士購買一手樓的需求管理,樓價始有回落跡象。紐西蘭今年8月也通過了類似的限購令法案,詳情可參考我早前的簡介[19]。香港彈丸之地,政府竟想以增加土地供應之法來壓抑難以負擔的樓價,若非天真,可能因為政府官員是賣地的既得利益者!

事實上,除了我在2015年的文章[20] 所引述的三項研究結果否定或質疑有關增加土地供應能壓抑樓價的假想外,近年再有三份學術研究分析同樣否定增加土地供應對壓抑樓價的成效!

第一份是香港大學房產建設系的三位學者在2016年發表的國際期刊文章 [21],研究找不到證據支持有關政府的土地供應對樓價有影響的假想,相反,他們發現樓價反而影響土地供應,這與上述BIS的研究結論相似:

" By applying a Granger causality framework, we find this expectation unrealistic as there is no evidence supporting the claim that changing land supply via government land sale programme would impact on housing prices. However, it is found that housing prices do Granger-cause land supply under the Application List System which implies that private sector is more responsive to market changes than the government, [21]

第二份是理工大學三位學者在2015年發表的國際期刊文章 [22],研究質疑土地供應增加是否等於房屋供應增加?所以題目直接問:《土地供應不足是否房屋供應不足的根本原因?香港的實證研究》,結論是房屋供應數量與政府的土地供應數量無關!以增加土地供應來增加房屋供應未必有效,原因是發展商可千方百計拖延賣樓,令房屋供應與土地供應不同步。

" By analyzing time-series data, it is found that the new housing supply in Hong Kong is independent of the land supply by government, which means the policy of increasing land supply to increase housing supply may be ineffective. " [22]

第三份是城市大學經濟與金融學系的兩位學者在2015年發表的國際期刊文章 [23],他們的研究同樣發現增加土地供應不一定增加房屋供應,加上貧富懸殊可以造成樓價不能負擔:

"Consistent with previous studies, we confirm that merely increasing the land supply may not increase the housing supply. We also find preliminary evidence for widening income inequality, which, when combined with unavailability, can lead to unaffordability in the housing market." [23]

事實上,文章引述另一份早自1999年由美國和澳門的經濟學者共同發表的一篇文章 [24] 已經指出,發展商以利益最大化為本,加上香港的私樓市場有寡頭壟斷,如果增加房屋供應會影響股東的財富利益,他們當然不會執行。

須知道,供應與需求並非兩項完全獨立的變數,可以鎖定一項,然後去找另一項對樓價的影響,更何況政府所指的是增加土地供應,從而增加房屋供應,再從而壓抑樓價,好比隔山打牛,能否有效實在存疑,邏輯能否說得通也成疑問。最近另有兩份研究發現,供應不但未能壓抑樓價,反而帶動需求,甚至成為造成樓價不能負擔的原因:

第一份是Bramley and Watkins (2016) 的文章[25], 他們發現樓宇供應會帶動樓宇需求,因為增加房屋供應可能會引致家庭組成的增加,需求上升了,供應增加也未必能夠壓抑樓價。這在研究界稱為「供需互為因果理論」(Circularity between Supply and Demand),Bramley 早自1995年已經就英國的房屋發展與家庭組成預測發表文章 [26],指出當某地增加房屋供應會引來區外家庭移入,需求增加變成自我實現的預言:

"... projections led to 'circularity', in effect a self-fulfilling prophecy that building X number of houses in a given location would result in that number of households moving to that location. They argued that 'the projections approach to planning is misleading – it is in fact not based on a neutral assessment of housing need.'”[26]

當然,由於政府官員須要顯示大有為,希望向市民表達政府有能力透過土地供應政策來調節樓價過高的問題,總不想承認政府對樓價飊升束手無策,因此即使明知落錯藥,明明沒有科學證據支持政策,也要胡亂吹噓土地供應政策是唯一解決辦法。

其實沒有實證的猜想一旦變成政策可以遺害深遠,公共政策建基於科學實證的重要凌駕一切,因為真正的科學方法不會說謊,反而官員、政客和商人們往往為了私利而欺瞞公眾。現在的客觀事實是政府就有關增加土地供應能夠壓抑樓價的科學證據一項都未能提出過,相反,能夠否定或質疑兩者關係的研究卻愈找愈多。

正如張五常 (2001)的《科學說需求》[27] 所講,所有理論必須經得起科學驗證,若有必對的理論,永遠不能驗證否定的,科學上稱之為套套邏輯,是沒有用的邏輯!
其實要科學地驗證供應不足導致樓價不能負擔是一項難度極高的挑戰,大家不宜輕視,除了因為供需可互為因果外,所謂的供應不足其實是指甚麼?張五常(2002)的《制度與選擇》[28] 寫了以下精彩的一段,叫人拍案:

『「過剩」是供應量大於需求量的差距,「短缺」是需求量大於供應量的差距。然而,需求量與供應量是經濟學者想出來的「意願」之量,並非真有其物。
於是「過剩」與「短缺」也是經濟學者腦中的想像,在真實世界不存在,從前沒有,以後也沒有。

……「短缺」是因為經濟學者的思想有所短缺。「過剩」是指多餘,應該廢除。』[28]

參考

[1] 綠色和平 (2018) 六成二市民無信心覓地令樓價回復可負擔水平,5月9日
[2] Holman, J. (2017) Housing affordability: Is more supply the answer to driving down prices?, ABC News April 25
[3] Favara, G. and Imbs, J. (2015) Credit Supply and the Price of Housing, The American Economic Review 105(3), 958-992.
[4] Justiniano, A., Primiceri, G.E. and Tambalotti, A. (2015) Credit Supply and the Housing Boom, Federal Reserve Bank of New York – Staff Report No. 709, Feb.
[5] The Economist (2018) Global cities house-price index, Aug 9
[6] Richter, M. and Werner, J.G. (2016) Conceptualising the Role of International Capital Flows for Housing Markets, Intereconomics, 1-9. DOI: 10.1007/s10272-016-0593-z
[7] Bureau of Statistics (2018) Residential Property Price Indexes: Eight Capital Cities, May 2018, Australian Government.
[8] Land Registry (2018) Statistical data set: UK House Price Index: data downloads May 2018, UK Government.
[9] Sa, S,F. and Wieladek, T. (2011) Monetary Policy, Capital Inflows, and the Housing Boom, Working Paper No. 80, Globalization and Monetary Policy Institute, Federal Reserve Bank of Dallas, US.
[10] Sa, F. (2017) Effect of Foreign Investors on Local Housing Markets: Evidence from the UK, working paper, School of Management & Business, Kingís College London.
[11] Fereidouni, H.G. and Tajaddini, R. (2016) Foreign Investment in Residential Real Estate in Australia, Housing Prices and Performance of Real Estate-Related Sectors, 22nd International Panel Data Conference, 28-20 June, Perth, Australia.
[12] Guest, Ross S. and Rohde, Nicholas (2017) The Contribution of Foreign Real Estate Investment to Housing Price Growth in Australian Capital Cities (September). Abacus, Vol. 53, Issue 3, pp. 304-318. Available at SSRN
[13] Wokker, C. and Swlerings, J. (2016) Foreign Investment and Residential Property Price Growth, Treasury Working Paper 2016-03, Australian Government.
[14] Ghollpour, H.F. (2013) The effect of foreign real estate investments on house prices: evidence from emerging economies, International Jourrnal of Strategic Property Management 17(1),
[15] Tillmann, P. (2013), Capital Inflows and Asset Prices: Evidence from Emerging Asia, Journal of Banking and Finance, 37, 717-729.
[16] Yiu, M.S. and Sahminan, S. (2017) Global Liquidity, Capital Inflows and House Prices in ASEAN Economies, International Real Estate Review, 20(1), 105-126.
[17] Chow, H.K. and Xie, T. (2016) Are House Prices Driven by Capital Flows? Evidence from Singapore, Journal of International Commerce, Economics and Policy, 7(1), 1-21.
[18] Cheung, Y.W., Chow, K.K. and Yiu, M.S. (2017) Effects of Capital Flow on the Equity and Housing Markets in Hong Kong, HKIMR Working Paper #01/2017, Hong Kong Institute for Monetary Research.
[19] 范國威、姚松炎 (2018) 澳紐與中國房屋限購令的分別,明報8月17日
[20] 姚松炎 (2015) 請用科學證明樓價高企的原因,端傳媒9月12日
[21] Ling-Hin Li, Siu Kei Kelvin Wong, Ka Shing Cheung (2016) Land supply and housing prices in Hong Kong: The political economy of urban land policy, Environment and Planning C: Politics and Space Vol 34, Issue 5, 2016
[22] Huang, J., Shen, G.O. and Zheng, H.W. (2015) Is insufficient land supply the root cause of housing shortage? Empirical evidence from Hong Kong, Habitat International 49, 538-546.
[23] Leung, C.K.Y. and Tang, E.C.H. (2015) Availability, Affordability and Volatility: The Case of the Hong Kong Housing Market, International Real Estate Review 18(3), 383-428.
[24] Lai, N. and Wang, K. (1999). Land-Supply Restrictions, Developer Strategies and Housing Policies: The Case in Hong Kong. International Real Estate Review, 2(1), 143-159.
[25] Bramley, G. and Watkins, D. (2016) Housebuilding, demographic change and affordability as outcomes of local planning decisions: Exploring interactions using a sub-regional model of housing markets in England, Progress in Planning 104, 1–35
[26] Bramley, G., Watkins, C. and Council for the Protection of Rural England. (1995) Circular projections : household growth, housing development and the household projections. London: CPRE.
[27] 張五常(2001)《科學說需求:經濟解釋 卷一》,香港:花千樹出版社
[28] 張五常(2002)《制度與選擇:經濟解釋 卷三》,香港:花千樹出版社

本文獲信報財經月刊同意,轉載自:姚松炎 (2018) 增土地供應遏樓價? 恐隔山打牛,信報財經月刊,499,10月

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