Category Archives: Political Economy

社評﹕AI革命席捲全球 政府須積極回應 – 20170901 – 社評 – 社評 – 明報新聞網

「人工智能」是今年最熱的議題,人云亦云的情況和三兩年前「大數據」不遑多讓。香港的「AI教育」其實不差:很多中小學都有Lego機械人隊。問題是學生無論多喜歡製作機械人,最終選擇以數據科學作為職業的數目相當少。這一來是因為香港的大學學位分配由政府主導,二來過去二十多年來政商界對科技的不重視,已經使香港的高科技產業遠遠落後週邊地區。
以香港科技積弱的程度,我相信新加坡和深圳一點都不擔心來自香港的競爭。當社會情況每況愈下,香港最大的優勢恐怕快要剩下作為走資港的地步了。

 

《金融時報》提及我以深度學習—依家興叫「人工智能」—估計車牌拍賣價錢的研究。
My deep learning paper on predicting license plate auction prices made it to Financial Times! This is actually the first paper in a series: followup papers will use the prediction model to look into various investment anomalies. Somewhere down the road there will also be a field experiment where we will provide auction participants with an app to gives them estimates in real time.

(Thanks to James Ko for sending me the article!)

 

特朗普與689

在網上見到有不少本土言論對特朗普的作風大表認同,認為是對左翼人仕的打擊。 我覺得這是十分奇怪的看法 。
 
特朗普由參選開始已經謊話連篇,政策民粹至上。上任後不顧利益衝突,政策閉門造車,用人唯親—最新消息是他從國家安全委員會裏免去三參軍參謀長及國家情報局長,只留下一眾親信—還起用了一個不知所謂的發言人。有沒有覺得這樣似曾相識?這分明就是美版689。
 
在特朗普當選之前我跟我的美國朋友說。我們香港過去五年所經歷的,你們也要經歷。結果特朗普比689更厲害:還不到一星期就已經把美國的政治道德底線推至歷史新低,更不用說美國總統的一個決定就可以讓無數人家破人亡。
 
有人會說特朗普是民選出來的,管治完全合法。這個說法沒錯,不過689的管治也是完全合法,又不見得大家覺得應該乖乖就範。而說到民意支持,美國和香港一樣也是用間選,特朗普和689一樣都沒有大多數市民的支持。689在上任之初,還受不少港人歡迎呢!
 
在今次移民禁令事件中的另一個觀察,是舉世的執法機關基本上都是唯命是從。在上位者的要求,前線人員基本上都會執行。如果說美國人民應該接受特朗普的政令,那香港市民亦都一樣。如果這樣,大量於去年被捕、受迫害的年輕人,又有誰為他們伸張正義?

Pay for the Wall with Tariff

The rumor is that Trump is going to slap a steep tariff on Mexican imports to pay for the border wall. This by itself is not surprising, as it is the only option that could be realistically claimed as making Mexico pay up.

The thing is, it doesn’t make any economic sense.

As anyone with common sense can predict, sellers of Mexican products will certainly shift a significant portion of the tariff to American consumers. Any decent ECON 101 would have taught the logic behind tax burden, and unless Mexico have no alternative use of their productivity, Americans consumers will have to pay a lot.

Some might say buying American would solve the problem. Or does it? Suppose every Americans decide to become true patriots and stop buying Mexican products—most likely out of patriotism to their wallets—such that import from Mexico drops to zero. Guess what? The tariff revenue will be zero. So ironically, the more patriotic Americans are, the more they will be paying for the wall.

This type of nonsense is what makes Trump so dangerous. He doesn’t care about the practicality of his orders and the whole country has no choice but to go along with him.

If Trump can put a gag order on EPA, he probably will try to do the same to BLS in the future. No more unemployment statistics. That would be the easiest way for him to claim credit for creating jobs.

有同學傳來CU Secrets個好grade批鬥大會,說GPA 3.5都怕無second hon云云。少年你們太年輕了,都未上Intermediate Macro,急乜?
Dear students, wait till you went through Intermediate Macro before you say everyone is getting high GPA.

係同一個地方教咗六年書,facebook上面一大部分嘅friends都係學系嘅學生,令到facebook嗰feed亦都好受學生影響。例如今晚個feed成日都係某位女同學嘅個人特寫。
Having taught in the same department for six years, a significant number of my facebook friends are students and alumni. This means that my feed is highly influenced by this group—like tonight, a portrait of a certain female student keeps popping up because too many of my facebook friends “liked” the photo.

研究助理入緊香港車牌拍賣數據,問:「點解 DGS 高 [DBS] 咁多」?
係囉,點解?
While entering Hong Kong license plate auction data, research assistant noted that #DGS fetched a much higher price than #DBS…as if it could have been the other way round.

全民退保學者與統計學

prediction

有同學問我如何看全民退保學者方案的計算,特別最近引起一番爭議的變數問題。我想從社會科學就統計運用出發,解釋一下問題所在。

在社會科學研究中,統計學的主要應用在於估算某因素對另一因素的影響:例如吸煙對存活率的影響,又或加價對需求的影響等。這樣的估算用的總是已有數據,分別只是數據有多新而已。因為已發生的事實只可能有一個,學者的責任就是盡力準確估算這個未知的事實。

因應上述的要求,傳統的社會科學統計訓練非常重視估算的無偏性(unbiasedness)。無偏性的意思是估算平均來說是準確的,而最具代表性的例子莫過於常見的線性回歸分析(Ordinary Least Square)。讀過計量經濟學的同學或許會記得(惡夢!)OLS的特點「BLUE」—Best Linear Unbiased Estimator。意思就是在無偏性的要求下,沒有其他線性模型比OLS更佳。

問題是,準確估算過往效果和就未來作出推算是兩會事。事實上,無偏性和估算的誤差範圍是有著取捨關係,統計學就此亦有相當的理論和驗證。在較進階的計量經濟學課程中—即係每年只有幾個本科同學會選修嗰啲—會教授一些相關的知識,但在整個經濟學課程中並非太受重視,因為如前所述,學者最需要的技巧是準確分析已發生的數據。因為經濟學以外之社會科學要求的統計學訓練更少,問題相信只會比經濟學更嚴重。

可能有同學會問,像全民退保這樣重要的社會議題,怎麼沒有統計學者去做嚴謹的推算?答案很簡單,因為對仕途有害無益。我過去已經解釋過,香港由教資會以降均看重學者著作的國際影響力,而像全民退保這樣的本土議題是上不了好的國際期刊,搞不好還要被人批評一番。吃力不討好,又何必自討苦吃?

《全民退保學者方案》:
http://www.legco.gov.hk/yr15-16/chinese/panels/ws/ws_rp/papers/ws_rp20151207cb2-398-1-c.pdf