????教師

????然后是無所不在的教師評分,，尤其是對大學教授的評分,。幾十年來，高等教育機構一直把對學生的問卷調查成績作為衡量教職員工工作表現(xiàn)的一部分,，現(xiàn)在大多數(shù)教育機構都要求課程結束后收集學生的評價,。如果你也像我一樣，相信教師的本職工作是教書,，好讓學生能學到并記住知識,，而不是給學生講段子、稱兄道弟,，那么你在衡量學生的評分時就要睜大眼睛,，要根據(jù)客觀衡量標準看看學生究竟學到了什么，然后再看看它與教師評分之間的關系,，你才知道學生的打分是否準確。

????好在給教師打分的做法已經實施了很多年,，對于學生評分與學生成績之間的關系也有大量的研究,。不過壞消息是，學生的課程評價,，幾乎與客觀標準反映的學生學習成果沒有任何關系——人們了解這個事實已經40多年了,。比如，一篇發(fā)表于1972年的論文研究了293名正在學習微積分課程的在校大學生,，結果發(fā)現(xiàn)：“學生主觀評分最低的教員,，獲得了最高的客觀得分,。”不過,，盡管學生評分對他們的學習成果沒有任何有價值的參考意義,，但這還是沒有影響評分在教育機構中的普遍使用。

????餐館

????和找醫(yī)生找老師相比,，對餐館質量和用餐體驗的打分往往會客觀一些,，引起的后果也更少。米其林公司從1926年起,，便聘請知識淵博,、經驗豐富的匿名專家，到全球各大城市尋找最好的用餐地點,。我們可以在TripAdvisor等網站上,，將米其林的評級方式與一般老百姓的評分方式進行對比。

????我選擇了兩座城市,，一座是離我住的地方很近的舊金山,，另一座是我和我妻子最近剛去過的巴塞羅那。我在2015年的米其林榜單上找到了這兩座城市所有獲得米其林星的餐廳,，然后看了它們在TripAdvisor上的評分,。以下是我的發(fā)現(xiàn)：

????巴塞羅那有21家一星或兩星的米其林餐廳。按理說,，這些應該是這座城市里最好的餐廳,，但其中卻只有一家登上了TripAdvisor的前10名，只有兩家進入了前50名,，只有7家進入了前100名,。其中一家名叫Nectari的餐廳擁有一顆米其林星，但它在TripAdvisor上僅排在第2262名,；另一家名叫Enoteca的米其林星級餐廳僅排在第1333名,。

????舊金山的食客兼打分員們對米其林的尊重也只是多了一點點。在舊金山的24家米其林星級餐廳中,，只有一家名叫Gary Danko的餐廳在TripAdvisor上排名前10,，但有6家米其林星級餐廳擠進了TripAdvisor的前50名。但作為整個舊金灣區(qū)僅有的4家二星級米其林餐廳之一的Coi,，在TripAdvisor上的排名卻僅為第562名,。

????至少對于這三個領域，可能還有許多其它領域來說,，消費者的評分往往與專家意見或客觀的衡量標準是不相關的,。當然，正因如此,，許多聲譽管理公司才會做得這樣成功,，因為聲譽是可以“管理”的（你可以從最好和最差的意義上理解這個詞匯）,，而與實際的質量無關。

????為什么評分會鼓勵錯誤的行為

????由于評分及其產生的口碑會產生經濟后果,，人們自然就會獲得足夠大的激勵去操控這套體系,。一種越來越普遍的方式就是雇傭“水軍”來發(fā)布虛假評價（或是開發(fā)軟件，不過軟件是比較容易探測和預防的）,。據(jù)一份研究預測,，在Yelp上，有16%餐廳評價是虛假的,。虛假評論往往更趨于極端,，口碑較差的餐廳通常更傾向于請“水軍”。IT研究機構高德納公司2012年的一份研究估算稱,，有15%的網絡評價都是虛假的,。2013年，紐約州檢察長“與19家企業(yè)達成一致,，后者同意停止撰寫不實評價,。”

????數(shù)不清的網站時不時都會冒出招聘水軍的帖子（然后這些帖子又消失了）,，讓他們寫自己的好話,，或是寫競爭對手的壞話。消費者網購前應該充分獲得各方面的評價信息,，以做出明智的購買決定,。保障這些評價的真實性在經濟上具有重要意義。因此,，亞馬遜和Yelp都在積極構建各種算法以篩除不實評價,，同時也在針對虛假評價的發(fā)布者采取法律行動。

????Teachers

????Then there are those ubiquitous teacher ratings, particularly of college professors. For decades, higher education institutions have used student surveys as part of the faculty evaluation process, and now most places mandate end-of-course student evaluations. If, like me, you believe that the fundamental job of a teacher is to teach—to impart knowledge that students learn and retain—as contrasted, for instance, with providing entertainment or becoming students’ best friends, then it seems reasonable to measure accuracy by examining the relationship between teacher ratings and what students learn through an objective measurement.

????The good news is that teacher ratings have been done for a long time and there are numerous studies of the relationship between student evaluations and learning. The bad news is that student course evaluations do not have any relationship with objective measures of what students have learned—a fact that has been known for more than four decades. For instance, one paper, published in 1972, studied 293 undergraduates in a calculus course and found that, “Instructors with the lowest subjective ratings received the highest objective scores.” The fact that student ratings do not offer any valuable insight on how well students learn has not affected the prevalence and use of the ratings.

????Restaurants

????Restaurant quality and the dining experience are both more subjective and also have fewer consequences than choosing the right doctor or getting a good teacher. Michelin has, since 1926, employed anonymous, knowledgeable, experienced experts to go to cities all over the world and find the very best places to eat. We can compare how Michelin rates restaurants with the same restaurants’ ratings made by the general public on sites such as TripAdvisor.

????I selected two cities, San Francisco, near where I live, and Barcelona, a place my wife and I recently visited. I looked at the 2015 Michelin lists of the places that earned stars (in San Francisco, I considered only establishments located in the city itself) and also ratings on TripAdvisor. Here’s what I found.

????Barcelona has 21 one- or two-star Michelin restaurants. Of the Michelin-rated establishments, presumably the very best in the city, only one is in TripAdvisor’s top 10, only 2 are in the top 50, and only 7 of the 21 ranked in TripAdvisor’s top 100. Nectari, with 1 Michelin star, ranks 2,262 on TripAdvisor, and Enoteca ranks 1,333.

????Diners/raters in San Francisco agree with Michelin only slightly more. Of San Francisco’s 24 Michelin-starred restaurants, one, Gary Danko, is in TripAdvisor’s top 10, but 6 are in the top 50. However, Coi, one of four places in the entire Bay Area that earned two Michelin stars, ranks just 562 on TripAdvisor.

????At least for these three domains, and quite possibly many others, ratings by consumers—of restaurants, academic instruction, or medical services—are quite uncorrelated with either expert opinion or objective measures of performance. This fact, of course, is precisely why companies in the reputation management space can be successful—reputations can be “managed” in the best and worst sense of that term, regardless of actual quality.

????Why ratings encourage the wrong behaviors

????Because ratings, and the reputations those ratings create, have economic consequences, there are, unsurprisingly, substantial incentives to game the system. One increasingly common way of gaming the system entails hiring people (or developing software, which is fortunately easier to detect and prevent) to post inauthentic reviews. One study estimated that 16% of the restaurant reviews on Yelp were fraudulent, that fraudulent reviews were more extreme, and that restaurants with weak reputations were more likely to commit review fraud. A 2012 study by IT research firm Gartner estimated that 15% of online reviews were fake. In 2013, New York State’s attorney general “announced a deal with 19 businesses that agreed to stop writing fake reviews.”

????Numerous websites pop up (and then disappear) offering to hire people to write positive reviews about you and negative reviews about your competitors. Online purchasing is supposed to give customers access to informative reviews before they make a purchase decision. Maintaining the integrity of these reviews is economically important. Not surprisingly, then, both Amazon.com and Yelp have been increasingly aggressive in their attempts to build algorithms that weed out fake reviews and also to initiate legal action against their perpetrators.