Categories
读书有感

最近读paper的一些领悟

读paper易,做model不易,且读且珍惜。下面仅为个人半夜胡言乱语,轻拍~

最近扫paper的数量没什么下降,但是深入读全文的paper越来越少。一个原因大概是很多working paper 研究的问题我不怎么关心?毕竟不是读书的时候需要读很多paper来应对coursework presentation和literature review...

说说一些感受这样。看paper首先是看标题,有没有特定的关键字;有的话再去看下一步摘要,有没有有意思的地方,无论是建模方面还是结论。摘要有意思的话就标记出来,待扫完目录后去打印个别全文细细咀嚼。感觉现在扫working paper的功力越来越纯熟了,一个小时完成上述工序扫个十篇左右这样。

但是比较哀伤的是我发现大部分选出来的paper还都能读懂,尤其是实证的paper,清一水的不是DID就是RE或者RDD,最多来个IV。读起来更有意思的地方怕是背景描述这块,有很多历史人文地域常识可以了解。我想说那个ATE不是不重要啦,但这货真的不稳定(随时间迁移),做一个时间节点上的估计有多大的概率会历史重演呢?而且很多时候是需要多个因素共同作用的,就跟个化学实验似的,控制的除了原材料还有温度湿度气压等等,实验室里面这些客观条件可控,但经济发展中不可控的甚至不可观测的客观因素实在是太多了。计量更多的框架还停留于单因素分析上(当然单因素已然分析不易),是不是有点落后于时代的诉求呢?唉可能还是要期待数学工具、统计理念对于关系数据处理的更深理解吧。现在的network model还是孱弱了一点。

默默的再补充一个实践中在大数据(big volumn big dimensions)客户数据建模中的体会。很多的时候我们会倾向于找客户的原始特征,所谓的demographical variables,性别啊年龄啊收入啊。但是除了facebook这样真人社交网站,谁会告诉网站自己是男是女年方几何呢?然后为了找这些”珍贵的”数据,要不就是通过现有的数据来猜,比如买女士用品的八成是女性;要么就是通过调查来获取一部分人的真实社会属性。然后呢?扔到模型里面回归去...

我想说,若是前一种,何必绕着弯子从可观测的数据生生的去猜不可观测的数据,然后再用猜出来的数据去预测其他东西?直接用可观测的数据好了。本来就是社会属性->特定可观测行为->预测未来行为这样的路径(比如我知道啊买尿布啤酒组合的八成是新晋爸爸,但是我只要知道你买了尿布啤酒日后就也需要婴儿车日后消费潜力巨大就足够了嘛,我干嘛一定要去知道你是男性已婚已育?看看你买的尿布牌子我大概也知道你家的消费层次和接下来的品牌层次偏好了,何必去苦苦的猜你的收入?),有点像经济学里的“显示偏好原理”,或者有向的贝叶斯网络这样(给定上层节点信息,上上层节点信息无用),何必这么折腾...若是后一种,还需要去费时费力不讨好的调查?又不是以前数据尤其是观察维度稀缺的时代了。每次见到刚被象牙塔教育好的遵循123456黄金律步骤出来的建模者,我都忍不住先深深的吸一口气冷气然后苦口婆心的讲一下为什么这些东西其实不那么重要...

都是被现有的实证paper毒害的,动不动就是入户调查数据。哎,人家是做田野实验的需要手工搜集数据各种来之不易,和你们玩大数据的到处都是蛛丝马迹不一样啊!干嘛只会比着葫芦画瓢,明显使劲的方向不怎么对嘛。学界没数据啊所以没办法,业界一堆数据还愁数据搜集?随随便便做个随机试验前后数据爱取多少取多少...喵,尤其是做预测模型的,其实可以不用那么折腾呀。读paper易,却也是取其精华弃其糟粕,玩的灵活才开心嘛。

再啰嗦一句好了,学计算机和数据挖掘出身的只学怎么在现有数据基础上建模,不学基本的数据搜集实验设计这些统计理念,所以不会往这边想;学统计的又被一群没玩过大数据的长江前浪所禁锢,框架就在那里,你见或不见。估计等现在这一辈成熟了下一辈人就真的是站在巨人的肩膀上了。

Categories
网络新发现

Kindle PaperWhite 电源键失灵/无法唤醒/无法点亮屏幕

今天园主的kindle抽风了,除了连上电脑以外,一律无法唤醒(没变砖)。首先猜测电源键坏了,然后上网搜...有人云需要80元去电脑城修,呜啊!这个pw才入手不到一年啊!果断先拆机看看什么情况(好吧,这已经是我第三个kindle了,前两个的尸体都被我拆过,然后彻底的寿终正寝了)。我心里边拆边默念,这一定是我拆的最后一个kindle...

Pw比以前的kindle好拆,前面的壳纯属装饰,硬粘上去的,用瑞士军刀最薄的刀片撬开一角就好了。然后一圈螺丝拧下来,嗯,顺利地脱掉后盖。咦,怎么没问题啊,没有零件掉下来啊,怎么触电源触板还是不能唤醒。正当我打算拆电池的时候,又开始网上搜,这次居然搜到了kindle paperwhite的唤醒套。咦,这货居然可以有唤醒套?然后果断去拿ipad唤醒皮套试试。依然无效。

垂头丧气的,继续搜。有人再秀如何DIY皮套,看了一眼原理大概是磁铁感应。还是不死心的去测试,发现ipad的皮套可以唤醒ipad,应该是有磁性啊。难道是不够强?于是满屋子开始找磁铁。一开始想找个废耳机的磁铁,后来睁眼一看,这不是还有几个冰箱贴嘛!果断拿过来试试。一、二、三!绕了一圈,kindle居然亮了!然后电源键恢复如初!

这是什么原理....想不通也懒得再去想了,大家类似的情况可以先找个冰箱贴试试。大概是白天kindle和ipad、笔记本、耳机之类裸奔混在一起,有磁性干扰,触发了什么机制?后面强磁铁干扰回去就好了?噗。

Categories
读书有感

英文写作笔记(二):避免废话太多

依旧从BerkeleyX: ColWri2.2x Principles of Written English 抄过来的。我真的对这门课是相见恨晚!呜呜,我写英文各种罗嗦(楼下群众:你中文更罗嗦好不好?你看落园多少废话?)

ps 中间有段讲写作语气的我没抄过来,这个感觉和语言就无关了,更多是用词的精准...

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what causes wordiness?

Wordiness is using more words than you need to in order to write what you mean.  Everyone has a tendency to be too wordy at times. Some of the causes of this wordiness are:

- Trying to sound too formal or academic. Unfortunately, in academic writing, there are a lot of examples of wordy writing. This doesn't mean you have to model your writing on bad examples. Your readers will always appreciate if you state your ideas clearly, and using no more words than needed.

- Not knowing more precise vocabulary.  For example, saying, She ran quickly to the store can be made somewhat less wordy, and more precise, by saying: She raced to the store (race=run quickly). Finding the right vocabulary can help you cut down the number of words you use. Every reduction helps, even if it's only a word or two.

- Using too many unnecessary and vague modifiers.  Typically, modifiers like really, very, quite, and similar words add no meaning to your writing. If you need to modify a word, find precise modifiers. For example, instead of There's a really tall building near my house, write: There's a 50-story building near my house. 

- Using too many prepositional phrases or possessives. These types of phrases can add length to your sentences, often unnecessarily. So, instead of The car belonging to Mr. Wang is in the garage [10 words], write: Mr. Wang's car is in the garage [7 words].

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Writing less wordy prose

Categories
读书有感

英文写作笔记(一):常见写作方向性错误

下面是抄过来的...来自:BerkeleyX: ColWri2.2x Principles of Written English。读完觉得我的英文写作真的是没受过正规教育...哎。

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There are two main sources of error in diction:

1. Choosing the wrong word. This can happen because of confusion between homonyms (words that sound alike but are spelled differently), or because the meaning of the word isn't fully understood.

2. Choosing colloquial, or less formal spoken language when standard or more formal language is called for (or vice versa). In academic writing, formal diction is generally expected.

Here are 21 common errors made in writing formal diction. How many of these usage errors have you made?

1. A lot/lots of

Colloquial: Diana likes her apartment a lot.
Formal: Diana likes her apartment very much.

Colloquial: There are lots of books in our library.
Formal: There are many books in our library.

2. Among/between
(Tip: Among involves more than two; between involves only two)

Colloquial: Discussions between our group members were often very lively.

Discussions Formal: Discussions among our group members were often very lively.

3. Around/ about
(Tip:  Don't use around to indicate time, distance, or other quantity.)

Colloquial: The class usually begins around nine.
Formal: The class usually begins at about nine.

4. Badly
(Tip: "Badly" is not a substitute for "very much.")

Colloquial: The team wanted to win really badly.
Formal: The team wanted desperately to win.

5. Based off of

Colloquial: Based off of that information,  we can move ahead with the plan.
Formal: Based on that information, we can move ahead with the plan.

6. Because
(Tip: Don't use "because" after " reason.")

Colloquial: The reason for our flight delay is because of bad weather.
Formal: The reason for our flight delay is the bad weather.

7. A bunch/bunches
(Tip: Use bunch or bunches only for things that are bound or grow together, like bananas and grapes; it is not used for other countable nouns.)

Colloquial: A bunch of us are going to the movies tonight.
Formal: A group of us are going to the movies tonight.
Formal: There are three bunches of bananas on the counter.

8. Each other/one other
(Tip: Each other refers to two, one another refers to more than two.)

Colloquial: Everyone at the party wished each other a happy new year.
Formal: Everyone at the party wished one another a happy new year.
Formal: My sister and I wished each other a happy new year.

9. Guys

Colloquial: I hope you guys can join me at the restaurant.
Formal: I hope all of you can join me at the restaurant.

10. In / Into
(Tip:  "In" means "within" or "inside", while "into" refers to the motion of going from outside to inside.)

Colloquial: Bill went in the bus station to buy a ticket.
Formal: Bill went into the bus station to buy a ticket.

11. Infer/imply
(Tip: To infer is an act of thinking, to imply is an act of saying something.)

Incorrect:  I saw your memo about a noon meeting. Are you inferring that we should have lunch together?
Correct: I saw your memo about a noon meeting. Are you implying that we should have lunch together?

12. It's/its

 

Incorrect: The committee has reached it's goals this year.
Correct: The committee has reached its goals this year.

13. Kind of / sort of
(Tip: Don't use "kind of" or "sort of" when you mean "very" , "rather," or "somewhat." )

Colloquial: Jim was sort of angry when he learned we went to the park without him.
Formal: Jim was somewhat upset when he learned we went to the park without him.

14. Less than/fewer than
(Tip: Use less than only with uncountable nouns.)

Colloquial: There are less people in the store today than yesterday.
Formal: There are fewer people in the store today than yesterday.

15. Like / as
(Tip: Use "as" when comparing actions, "like" when comparing things.)

Colloquial: Alan wants to write a new essay, just like Sarah does.
Formal: Alan wants to write a new essay just as Sarah does.

16. Like / maybe
(Tip: Avoid using "like" and "maybe" when estimating; use "approximately", "perhaps" or "about" instead.)

Colloquial: There were like thirty people at my birthday party.
Formal: There were approximately thirty people at my birthday party.

17. Meantime

Colloquial: Meantime, the rain continued to pour.
Formal: In the meantime, the rain continued to pour.
Formal: Meanwhile, the rain continued to pour.

18. On account of

Colloquial: On the account of the weather, our plane was late.
Formal: Because of the weather, our plane was late.

19. Plenty

Colloquial: It has been plenty warm all week.
Formal: It has been very warm all week.

20. So
(Tip: Don't use "so" as a synonym for "therefore".)

Colloquial: Dmitry knew that I missed class, so he shared his notes.
Formal: Dmitry knew that I missed class; therefore, he shared his notes.

Colloquial: This week's homework is so difficult.
Formal: This week's homework is very difficult.

21. They're/their/there

 

Incorrect: Do you know if their going to the party?
Correct: Do you know if they're going to the party?

Incorrect: What is there address?
Correct: What is their address?

Categories
读书有感

Constitutional Law by Yale 听课笔记(三)

宪法修正过程。

第一次大的修正称之为Bill of Rights, 1791年通过。后面的修正案大都集中在某一段时间。

Bill of Rights 修正案1-12 十八世纪末十九世纪初

Civil War Amendments/Reconstruction Amendments 修正案13-15 十九世纪中期,civil war后

The Progressive Era Amendments 修正案16-18  二十世纪初

详细的列表在这里:http://en.wikipedia.org/wiki/List_of_amendments_to_the_United_States_Constitution

Bill of Rights主要的诉求是:

The Bill of Rights enumerates freedoms not explicitly indicated in the main body of the Constitution, such as freedom of religion, freedom of speech, a free press, and free assembly; the right to keep and bear arms; freedom from unreasonable search and seizure, security in personal effects, and freedom from warrants issued without probable cause; indictment by a grand jury for any capital or "infamous crime"; guarantee of a speedy, public trial with an impartial jury; and prohibition of double jeopardy. In addition, the Bill of Rights reserves for the people any rights not specifically mentioned in the Constitution and reserves all powers not specifically granted to the federal government to the people or the States.

Civil War Amendments主要是告别奴隶制度:

Their proponents saw them as transforming the United States from a country that was (in Abraham Lincoln's words) "half slave and half free" to one in which the constitutionally guaranteed "blessings of liberty" would be extended to the entire populace, including the former slaves and their descendants.

Progressive Era Amendments更多是现代化的标志:

The Sixteenth Amendment gave the federal government the power to lay and collect an income tax regardless of the source of that income.

The Seventeenth Amendment provided for the direct election of Senators by the people rather than by the state legislatures as the original Constitution called for.

The Eighteenth Amendment prohibited the import, export, transport, manufacture or sale of intoxicating beverages.

The Nineteenth Amendment gave women the right to vote.

最有趣的就是妇女投票权了。毕竟是需要男人们投票来决定妇女有权投票。一开始是从稀缺妇女的 Wyoming Territory州开始,然后扩展到全国。

最后的二战后的修正则主要是一些对于民主的更深入理解,比如总统任期的限制。