PHD的生涯

# The exam feedback conundrum

By this point in the semester, I have given two exams in my Calculus class and one in my Real Analysis class. Grading is always a pain, but I have struggled much more recently with what to say as I hand out the exams. Giving statistics on the exam might be helpful for students so they can see how they stand with respect to the rest of the class. But is that really important? Isn’t it more important that the student only know how they did, and perhaps how they can improve? I really don’t know the answer to this question. I used to never give statistics on the exam. If my students asked, I would say that averages and medians were not a great way to summarize their performance, and that they should really only worry about their own performance. But I have recently caved, mostly because I realized I was one of the few people who did not give any stats on the overall class performance, and the students were sort of expecting it. After a couple of awkward incidents this semester, I’m considering going back to my “no stats” policy.

The first thing to think about is why would you want to know how everyone else did? Especially if the professor doesn’t curve, and so the performance of others will not affect your own individual performance. So what does it matter if you were the only A, or one of the many A’s? But of course, it matters.  Everyone wants to feel like they’re doing better than average, so they want to know the average. The paradox here is that there have to be people below the average! I remember telling my Calculus students, on their first exam, that the median was an 89. I was congratulating them, because as a class they performed well. But as soon as I explained (to the few who didn’t know) that the median was the cut-off between the top 50% and the bottom 50%, a lot of them looked very concerned. They realized that 50% of them had gotten an 89 or less. So somehow, this makes the people who didn’t get an A feel worse, and at the same time it makes the people who did feel less special. So my attempt to congratulate and praise kind of backfired.

And then we have the problem of what that praise does to the students’ performance later. For example, the average and median on the second exam were a lot worse. And I know in part it was because the material got harder (the material always gets harder), but I wonder if maybe they got a bit complacent and overconfident, and decided to blow off this exam. Of course, I have no way to prove this, and because I had done it for the first exam, I gave them the stats for the second. One student asked for more information, like what was the spread of the grades. This is a good statistical question, but I don’t like to give the highest and lowest scores, since then I make the student with the lowest score feel really bad. I gave the highest score, because I decided no one would mind, and then the student with the highest score came up to me and said that that made them a little uncomfortable. I didn’t say any names or indicate that they had been the student with the highest score, but then I realized that their friends could probably figure it out, and I guess that’s something that people are not always comfortable with sharing.

This reminds me a bit of my Real Analysis exam, where the median was an A-. I wanted to share that with the class because the exam wasn’t easy, Real Analysis is not easy, and I wanted to congratulate them on their accomplishment. But again, my mistake was in forgetting that there were still people who had not done very well, and thus I was essentially making them feel very bad about themselves. I am also not sure if this improved morale in the class, since an A in Analysis, which would normally be exciting, now didn’t seem like such a hard thing to attain and thus was made less special.

Of course, it could be much worse. When I was in college, my Linear Algebra prof liked to hand out exams in descending order. So if your name was called first, you knew you had the best grade in the class. As names were called, you got increasingly worried. Whoever was called last had to do the long walk of shame to the front of the class to pick up their exam, which we all knew was the worst. I was called first only once, and I was very pleased with myself, so I guess the method did improve my self-esteem. I’m not sure this method helped anyone in the bottom half, though. In any case, I believe that this would be illegal due to FERPA rules, so it’s not even something to consider.

All of this is a long way to say that I’m considering not giving any statistical feedback on the exam. Maybe just focus on common mistakes and things to work on for the final exam, and perhaps I could take a bit more time on each exam and write personalized feedback on the exam instead. I do tell everyone who got less than a 70 to come talk to me during office hours, so that’s another place to give feedback and comments or suggestions on a student’s individual performance. It is tempting to praise a class that did well, but it’s possible that I’m doing that more to stroke my own ego (look how great a teacher I am!) than to improve their morale. Each one of them knows how they’re doing, and I think now that that should be enough.

How about you, dear readers? How much feedback do you give to the class as a whole on their performance in an exam? Have you had uncomfortable situations stemming from this? Do you have suggestions for how to praise the students without making others feel bad? Please share your thoughts in the comments section below.

# 博士这条船

```[回复本文][原帖] 发信人: WAMozart(含泪微笑的天使), 信区: PhD

，也好。

1.或许有人嫌太长了不想看，或许我的观点片面甚至偏激，或许我的经历太特殊而不具备

，海龟博士铺天盖地的。所以选择有些专业就意味着除非转行，否则一定要从一而终，读

。背点东西什么的，对我来说从来就是轻松愉快的事情，而逻辑推理是要了命的。这种孩

：高中的时候，家长和老师都希望我选理科，理由是男生嘛，理科拼一拼还是很不错的（

，又怎么知道还有各种测试性格、思维方式和职业倾向的科学测试呢？现在的孩子们要利

。而搞纯正的文科或艺术类专业，除非成为同行中的佼佼者，确实很难挣大钱。但我就不

2. 公认地，化学和生物是所有专业中读博士最苦逼的专业。所以一个生物学博士生的血泪

3. 对于真正适合读博士做科研并且真心热爱科研的人，什么都拦不住的。本文能够拦住的
，一定是相当不适合上这条船的人。其实你们像我一样，会在其他领域发挥自己的才能，

，花白头发的博士生并不罕见，而这类无止境地追求自身更高精神境界的勇士才最配被授

，只能问出这样一个问题：毕业之后我能干什么？

。生存问题得不到一个足够强有力的保证，谁都不会去考虑更高层次的需求，包括对什么

，另外一方面在美国博士毕业之后的收入通常来说并不比硕士乃至本科毕业的高太多。所

on and social time，以及最重要的健康，这样的代价，去谋求更上一层楼。所以通常来

2.   直接留在高校和科研院所。因为没有博士后经历，即使是国外名校博士毕业回到国内
，也得爬几年才有可能爬到副教授职位（二三流大学不用提了，那是养老和玩女学生的所

3. 去企业。国内目前一般的生物医药行业企业，刨去那些倒买倒卖试剂的皮包公司，给博

4. 其它零碎的出路。比如我今后的去向，做本专业英文SCI杂志的编辑，或者去果壳网之

5. 转行。好吧，可是如果毕业之后转行的话，为啥要读博士？不过到了山穷水尽的地步，

。我要说的便是那“热情，兴趣和灵感”。确实，在我刚涉足科研领域时，这三个词放在

ogram)的想法。于是我扣开老教授的办公室门说明想法，他同意给我指导，但项目由我自

。那篇文章确实是我饱含热泪写出来的，因为写作的时候老生物楼已经在施工改造了，那

PRP那两年中我们自己动手把论文上的文字变成手艺活，艰难也可想而知。不过我们都乐在

，兴趣，灵感，莫非是虚假的？绝不是！现在我恍然大悟，破灭的并不是我的兴趣、灵感

1.极强的自制力。因为极少有人会从骨子里热爱做科研，胜过喜爱花前月下饕餮大餐环游

2.狭窄的兴趣和有限的社会活动。经常要进城看音乐会？每天晚上要陪女朋友？得了吧。

3.说得不好听点，要有点geek。比如什么呢？比如我做学术民工时的那个老板，每天午饭

4. 家里有一定的财力，女朋友不很物质（或男朋友是大款），没被催着结婚。第一条是保

。或者，干脆搞基得了……

5.脸皮要厚，心脏要坚强。被老板骂得狗血喷头实属正常，实验一次成功可以马上去买彩

6. 不要往上比，要往下比。高中同学聚会，当年考试分数被自己永远秒杀的傻不拉几只会

O等等话题。此时，兜里只有几百块钱孓然一身来赴宴的博士生，须秉持“不该看的不看，

）硕博连读毕业，就在交大留下，拿到副教授待遇，去了美国做博后。父母都只有初中文

1.强大的逻辑思维能力。那位学霸数学经常拿满分，不光是靠拼命用功就能做到的。一些

，请文科的朋友来补充。理工科方面，大家知道，生物学是最偏文科的一门。尤其本科时

。算术之外说穿了都是文科那种要背的东西，在背的基础上再去融会贯通。即使到了硕博

。因为生命现象和活动的随机性、复杂性和动态特性太强，数学工具用来描述这些现象和

。我更主要的问题是得费好大的功夫折腾出一些勉强算是实验结果的东西，才够我写一次

，只要培训足够长的时间。而博士的价值在于把握研究方向，设计实验思路，trouble sh
ooting，以及销售自己的成果。除非导师每一个实验步骤都给你设计好，每一个结果会给

2.有极清晰并且得到严格执行的（阶段性）人生目标。

？如果不是取向异常，那就是阶段性人生目标非常清晰而且得到严格执行。我妈有个同事

）连电话都没法听短信都没法及时回，又穷得连送她一根最便宜的施华洛世奇项链都要咬

dry work，双手不沾鲜血的孩纸们），顶多能够延伸到化学化工这一类同为劳动密集型学

1.从入学那一刻起就牢记，你是SB，你是渣渣，你什么都不是。

。当然这是指学术圈至少中上游流域的情况。如果你希望毕业之后做一条下游的鱼，戴一

000多块，还是攻克不了。几年后我知道PCR只是比装枪头略微高级一点点的基础技能，要

，从零开始，跟着你的导师慢慢学。前提是你的导师确实是有学术水平的。如果不幸撞上

，我不鸟你的idea，但你还是要给我经费做实验的牛人。

2. 你是木头人，你是机器人。

；人家只要在晚上八点前把DNA样品放到楼下一个窗口，贴上自己实验室的条形码，第二天

，你在国内一个课题结题要由一位青椒带动几乎全体博士生像四大里面突击搞审计那样折

1.做实验要高度专心。我导师规定手机不得带入实验室，一开始我觉得过分，后来自己吃

，如果浪费了实验动物可能还要等很久才能订得到下一批，代价会非常惨重。比如给一排
ep管加试剂，标准做法是加完一管就把管子往上移一格以防一走神忘记自己加到哪一管了
。尤其往大体积比如一两百微升的溶液里加一微升的酶，全都是无色透明溶液，根本无从

2.底子不够厚就老老实实照规矩来，别乱创新。Protocol上的繁琐步骤，老板的奇异规定
，师兄师姐的古怪经验，可能照着做很麻烦，但别轻易地扔了它们。手艺活靠的就是经验
，很多经验可能看起来没道理甚至违反常理，但在你成熟到可以向别人系统地传授经验之

3.读文献，读文献，读更多的文献！二战美国海军名将“公牛”哈尔西被问到准备如何对

，读多少好文献决定了毕业时能发多少好文章。没有通读几百篇英文文献，不要跟别人说

。但这些“日本鬼子”必须杀掉。惭愧，虽然我读英文文献比大部分理工科学生轻松得多
，地铁上半小时足够我把一篇四五页的英文文章从头看到尾还不用字典。但我没读过多少

，因为偷懒而省下一个小时的文献阅读时间去玩，几乎一定会付出几十倍的时间去做徒劳

4.重视实验记录。做实验的时候用到的试剂仪器和方法，当时可能早已司空见惯，懒得重

，甚至先做了实验回头再写，记忆已经有误。实验结果也要妥当有序地存放好，电子数据

5.重视presentation skill的锻炼。我在美国时第二个导师传授了我很多经验，包括：做
presentation一定要是audience oriented，文字要少图表要多，严格控制在每张slide一

6.尽量多帮助实验室里的每一位成员。生物医药行业不仅是一个劳动密集型行业，而且非

，大家互帮互助是团队存在之最重要的意义。光说实验领域，怎么着也能数出至少一百种
，比如分子克隆（这其中的倒平板、转化、涂板、挑克隆、抽质粒、酶切、连接等步骤已

S-PAGE这种天天做的事情已经都不能列为技能了，这都成本能了。每个实验室可能用得到

。如果我本科时的数学物理等公共课能不挂掉那么多，凭专业课成绩和GT分数早就出国读

，就不可以有其它辅助方式。以其为单一标准，比如交大规定理工科博士必须发表影响因

——高校教师和院所研究员晋升的规定中关于发表论文质和量的部分一样，是我所知道的

，才能诞生。中国的博士培养制度为啥不允许培植这类珍贵果实的土壤存在？我们的博士

。最后只剩一两年时间，想做原创性研究？连失败一次的机会都没有。

，加上我自己做交换生期间的耳闻目见，算是有所了解。博士读个七八年，在美国太正常

，做到教授，尤其学术光环闪亮的，跟普通的贤妻良母几乎必有本质区别，这是不言而喻

，科学的质疑精神和创新精神等等，才是博士学业真正带给人的学术方面的财富。从小在

，那种大家勤于思考踊跃讨论的氛围，在国内几乎找不到。更不要说从早开到晚的讲座，

ao to Mozart中，在犹太裔美国小提琴大师斯特恩访华时所说的几段话中，我找到了这种

Being a musician is not a profession. It's not just a job, and it's not someth
ing occasional. It is the totality of your life , and your DEVOTION to somethi
ng in which you BELIEVE PROFOUNDLY. And you have to BELIEVE in order to make o
ther people BELIEVE.

Unless you feel that you will live with music, that music can say more than wo
rds, that music cay mean more, that without music we are NOT ALIVE. You don't
feel all that, don't be a musician.

Every time you take up the instrument, you are making a statement, YOUR statem
ent. And it must be the statement of FAITH, that you believe this is the way y
ou WANT to speak, not the way you are REQUIRED.

atement。这原话移到中国的学术圈，又有什么问题！

say yes to it.

，教育一个孩子，完善自己的心智，何尝不是一份需要投入无限精力，没有上下班概念，

ION to something in which you BELIEVE PROFOUNDLY? 要做一份事业，你怎能像只做一

，就有这些牺牲了正常人很多难以割舍的东西而DEVOTE到科学中的伟人。

tist？如果science和scientist被取代得毫无疑义，那如果你还年轻，还有机会，那就勇

# ［转载］一个library.nu倒下去,千万个电子书网站立起来

```作  者: zr9558

【 以下文字转载自 Mathematics 讨论区 】
【 原文由 zr9558 所发表 】

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# 身体到极限的6个标志：午睡也做梦 记性变得差

1.午睡一会儿也做梦。午睡可以给身体“充电”。然而，美国弗吉尼亚州马萨杰弗逊医院睡眠医学研究中心主任克里斯托弗·温特博士表示，午睡最长时间为30分钟左右，通常只处于浅睡眠状态。但是，如果你午睡时一闭眼，就开始做各种奇怪的梦，说明大脑严重缺少睡眠，迫不及待地想要进入深度睡眠阶段。

2.记性变差。美国哥伦比亚大学焦虑与相关疾病诊所主任安妮·玛丽·阿尔巴诺博士表示，有些身体健康的人记性不好。其实，这些人是“大脑超载”，激素变化扰乱了记忆功能，使人无法记住更多的内容，容易忘记近期的事情。

3.运动后更加难受。美国维克森林大学医学院妇产科教授萨拉·伯加博士表示，一般情况下，慢跑45分钟会让人感觉很轻松，但是如果你刚开始运动就感觉疲惫，就说明身体已经超负荷了。伯加博士研究发现，压力大的女性进行中等强度的运动，身体能量会供应不足，感觉疲惫乏力。

4.喝咖啡也会困。美国临床心理学家迈克尔·布里斯博士表示，喝咖啡后人的大脑活动会发生改变。如果咖啡因没起作用，就意味着身心已经极度疲劳，抵消了咖啡因的兴奋作用。

5.吃温和的食物也会加重泛酸。美国《身心医学研究杂志》刊登的一项研究证实，压力不会导致泛酸，但会加重泛酸病情。即使没有吃辛辣刺激的食物，泛酸症状仍然存在或更加严重，就说明压力过大。

6.头皮变敏感。美国宾夕法尼亚临床心理学专家理查德·弗雷德博士表示，压力通常会导致皮肤中神经肽和其他自然化学物质增加，引起炎症。这种炎症会以痤疮或酒糟鼻等形式爆发，有的还会导致血管收缩，使面部和头部的皮肤过紧、刺痛或敏感。

# [转载]The PHD GRIND – A PHD Student Memoir

http://www.pgbovine.net/PhD-memoir/pguo-PhD-grind.pdf

pguo-PhD-grind

http://pgbovine.net/PhD-memoir.htm

http://blog.sciencenet.cn/blog-379672-599410.html

Philip J. Guo

philip@pgbovine.net

http://www.pgbovine.net/PhD-memoir.htm

1 对追求博士学位可能感兴趣的本科生

2 当前正在寻求指导或鼓舞的博士生

3 想更好地理解博士生们的教授

4 聘用和管理有博士学位的人的雇佣者

5 工作在任何强烈需要自我驱动的创造性、竞争性领域的专家

6 对学术研究的过程好奇的受过教育的成年人（或早熟的孩子）

Philip Guo，2012年6月

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Dawson明确表示希望赶在2007年3月截止日期前提交那个顶层会议论文。他告诉我其他五位学生正在做什么，并且给了我一些任务选项让我从中选一个。我选择用Klee查找Linux设备驱动的新漏洞。设备驱动是使得操作系统可以与周边硬件设备如鼠标、键盘等进行通信的一个软件组。Linux操作系统包含成千上万的设备驱动用以和各种不同的周边硬件通信。设备驱动程序里的漏洞很难用传统方法找出来，并且有着潜在的危险性，因为它们能引起操作系统冻结或者崩掉。

Dawson相信Klee能够找出以往从未被发现的数千种Linux设备驱动程序里的漏洞。我记得考虑过尽管在论文中展示找到的Linux设备驱动程序里的漏洞会很酷，但我仍然不清楚这些结果怎么会对整个研究有实际的贡献。从我自己的理解来看，我将用Klee去查找新漏洞——已经存在的研究成果的应用——而不是想着怎样创新性地改善Klee。而且，我不知道我的工作会如何与其他五位的工作集到一起以能在3月交掉论文。然和，我相信Dawson应该胸有成竹并且有高超的论文写作策略。我只是参加了这个项目，我不想马上去问导师的想法。既然我被分配了一个具体的任务，那我只想一心一意完成属于自己的分工。

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Dawson和其他学生几周时间都在用Klee-UC工作。同时，他们让我继续用老方法查漏洞。他们计划用Klee-UC重查我用Klee手工查的漏洞以展示Klee-UC的有效性。在提交论文上，他们主要说的是Klee-UC能够几分钟内就完成自动查错而不需要任何调试工作，而不是曾经有一个苦逼的博士生（我！）日日单调乏味地调整Klee手动查错。

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ps：博士第一年的部分翻译完了，后面还有不少内容，我以后有时间再翻译。。