Detour

A post I wrote three years ago is still getting me a couple of comments/emails a day in regard to obtaining copies of solution manuals. In response I have set up a bulletin board to help facilitate the trading, begging for, and bartering of solution manuals. I am hoping that the site can become a solutions manual trading post on the net for needy graduate and undergraduate students to find eachother and offer whatever value they can to those lucky few that are in possession of the holy grail for students. Happy searching.

I have solutions manual to the following:
1.MWG.(hrd n soft copy)
2.ROMER.(hrdcopy)
3.SIMON AND BLUME (soft copy)
4.CASELLA AND BERGER (soft copy)
5. WILLIAM GREENE (soft copy)
6.JEFF WOOLDRIDGE (soft copy)
7.SARGENT AND LINQUVIST.(soft copy)
8.STOKEY AND LUCAS (hrd n soft copy)

I am looking for the complete solutions manual to Robert Feenstra’s book on International Trade. Please contact me at mranon1976@gmail.com, if you would like to trade any or ALL of these manuals for the one above. Please do not mail with any other offers, you will be wasting ur and what is far worse, my time.

Update: There are many more offers for trades that can be found here. I posted this trade as its own post because this guy has an entire graduate program worth of solutions. Happy trading

I was looking over a Casella & Berger, “Statistical Inference” 7th edition and have been pondering a question all night as a result.

A finite set is defined as…

A set S is finite if it has the same cardinality as some natural number n in N (The set of all natural numbers) . We then define |S| = n and say that S has n elements. A set is infinite if it is not finite.

A countable set is defined as…

A set S is countable if |S| = |N|. A set S is at most countable if |S| ≤ |N|.

Thus a set S is countable if there is a one-to-one mapping of N onto S, that is, if S is the range of an infinite one-to-one sequence.

Otherwise, the set is uncountable.

My proof skills have always been lackluster, and it has been well over a year since I last attempted a proof, so I was hoping someone who has some recent practice with proofs, set theory, or probability theory could help me figure out an example of an uncountable finite set. I am of the mind, at the moment, that there is no such thing. Casella & Berger give no example…does this mean such a set is not possible? A Google search of “finite uncountable set” and uncountable finite set” yielded less then lackluster results.

Update: Kerry mentions in the comments section that it is a bit strange that I do proofs in my spare time…Kerry prefers to bowl…Vinny likes to update his blog layout. To each their own!

I make it a policy to leave the toilet seat up. I can’t get blamed for peeing on it, and if a women is so scared that she might sit down while the seat is up, then she should look before she sits (obviously I relax this rule on Valentines Day and Anniversaries).

My wife has stopped trying to train me to put the toilet seat down; I can be a bit stubborn. But I hear in many houses with males and females using the same toilet the seat-up/seat-down debate can become quite heated. Leave it to the world of economics to try and solve this debate through the use of economics and game theory.

The toilet seat problem has been the subject of much controversy. In this paper we consider a simplified model of the toilet seat problem. We shall show that for this model there is an inherent conflict of interest which can be resolved by a equity solution.

Consider a bathroom with one omnipurpose toilet (also known as a WC) which is used for two toilet operations which we shall designate as #1 and #2. The toilet has an attachment which we shall refer to as the seat (but see remark 1 below) which may be in either of two positions which we shall designate as up and down.

Toilet operations are performed by members of the human species (see remark 2 below) who fall into two categories, popularly designated as male and female. For convenience we shall use the name John to refer to the typical male and Marsha to refer to the typical female.

The performance of toilet operations by John and Marsha differ in a number of respects. The costs of these operations are peculiar to the respective sexes and are fixed except with respect to the position of the toilet seat. In particular:

Marsha performs toilet operations #1 and #2 with the seat in the down position. John performs toilet operation #1 with the seat in the up position and toilet operation #2 with the seat in the down position. If the seat is in the wrong position before performing the toilet operation the position must be changed at an average cost C. Optionally the position may be changed after performing the toilet operation, also at an average cost C. (Changing the position of the seat during the performance of a toilet operation is beyond the scope of this note and is definitely not recommended.)

The optimal solution is

In the morning John leaves the seat up after performing #1.
In the evening he puts it down.

I still say Marsha should take responsibility for her own safety in this matter.

The realization that I have a true disdain for mathematical proofs came to me late in my educational career. I am convinced that this could have been avoided by a formal and structured introduction to them. I sometimes wish I had paid more attention to my mathematics education in grammar school and beyond. Trying to pick up proofs in my first year of an economics PhD was a recipe for disaster. I took tons of math as an undergrad, but somehow avoided doing all but the most trivial proofs throughout my acquisition of a degree in statistics. Hell, when a proof was listed in any of my textbooks I would skip right over them…’they aren’t material’, I would think to myself. It was eye-opening for me to find out that the proofs had a structured language. I always thought that epsilon, delta, etc. were just pulled out of thin-air to confuse the reading of proofs. The thought that delta almost always means the change in just didn’t occur to me and probably explains why I never took the time to read the gibberish.

Adam Osman has a link to a graduate mathematics student named Fernando Q. Gouva written to convey what he learned by teaching real analysis to undergrads. After reading the article I am convinced that Fernando will b e an excellent professor of mathematics. Teaching and thinking about how to teach complex subjects often takes a back-seat to research prowess in the hiring and retaining of professors. So to see a graduate student actively involved in introspection about how to better teach a subject is refreshing. Fernando almost made me want to pick up some of my advanced mathematics texts and have fun for the first time in nearly a year. Cool. Check out the article if you have the time and inclination.

Masa Kudamatsu, a PhD student at LSE, has collected quite an impressive list of links that address the transition from a lowly undergraduate to a mighty economics professor. Every stage of the process of becoming an economist is covered.

There are multiple links covering the following subjects…

Applying for PhD programs in economics

How to proceed with your PhD life

Choosing a research topic

Building a theoretical model

Seminar Presentation

Presentation of your research (either in a seminar or in a paper)

Writing a paper

Going on the job market…

After becoming an assistant professor…

Great work Masa.

I can tell by the spike in hits to my home-site that the application process for wanna-be economists hoping to get into a great graduate economics program (with funding…of course) is in full swing. Winslet in Washington DC has a site called Sophomore in the Capitol which is pretty good. Check it out if you want to reminisce about the pain and turmoil of the process (or if you aspire to one day put yourself through the punishment that is an economics PhD).

Winslet has collected some quotes about Econ Math Camp…

At Berkeley:
“Math camp was a horrible experience, but I got through it and have to say that Advanced Calc at AU really did help. I didn’t at all know as much analysis as I should have, but at least I had some idea what a proof was. (I think I would have cried if I had gone in with no analysis background at all.) The macro, micro, and metrics theory courses aren’t incredibly interesting all the time, but they’re probably not as dry as they could be. ”

- my former AU classmate

At Boston U:
“Guys, Math Camp is the BEST. Seriously! It’s so good to be around people who weren’t embarrassed to respond to the question, “What are you doing this summer?” with “Going to math camp.” Or, at least it is good to be around people who were also mocked for it.”

- fomer IIE RA

At Northwestern:
“Math camp, on the other hand, is very hard. The 3hr lectures are followable, but the (daily) problem sets are pretty brutal, and just about nobody is getting the answers before they give them to us for the discussion section (fortunately, there are no grades). The material they are reviewing is supposed to be the math you will need to know for the first year. We have Real Analysis & Topology, Linear Algebra, MV Calc, Optimization, and Probability sections, all 2-3 lectures each. The students are on very different levels math-wise. The ones who seem to be doing the best appear to be those who just graduated undergrad w/ a math major. Those of us who have been out of classes during the past couple years are having to re-learn quite a bit. We have a textbook (Simon & Blume, Mathematics for Economists) but the book is very simple compared to what they are teaching in class. I’m hoping that knowing the stuff in the textbook will get me through the year. ”

- former IIE RA

I don’t miss doing math for hours upon hours each day. An economics Ph.D seems to have an endless string of equations and proofs in the first year. I look at old freinds websites, such as this, and thank god I left that behind. I never found joy in math equations and proofs and will not miss that part of graduate school life.

One thing I do miss about my old life as a student is writing. I used to write everyday. Whether it was my blog, ideas in a journal, or notes in the margin of whatever book I was reading at the time. I just don’t write anywhere near the amount I used to when I was in school. I miss it.

What I can’t figure out is why this is. I have way more free time then I used to. I haven’t lost my desire to explore ideas…I just don’t do it as much anymore. I have to make a determined effort to change this.

First, I need to understand why this has happened?

John Morrow over at econgrads.com is taking a survey.

If you were, are, or will be in an economics graduate program, please take the following survey at:

survey.econgrads.com

Your participation will help address the issue of solution manuals and graduate education in general. Please distribute the address to non-users of the site as I’m afraid the frequent users are a fairly biased sample. Thank you, and especially thank you to contributors who have made the site possible.

The University of Virginia has a cheating scandal brewing in the economics graduate department this summer which has implications for every student I have ever met in an economics PhD program. According to Inside Higher Education magazine…

An “alarmingly large fraction” of the first-year class of economics graduate students at the University of Virginia were involved in a cheating incident that came to light this month, according to the department chair.

Department officials said that some problem sets from textbooks used in introductory graduate economics courses have answer keys online. At least one student found answers for a course taken by all first-year students, and apparently shared the information with classmates. Though the solutions were apparently available, David Mills, chair of the economics department, said students should have “known it was off-limits,” but that they instead “used it without the professor being aware.”

I find it incredibly hard to believe that the faculty of any economics graduate department does not know that within a month of arrival most students have access to solution manuals for the books and up to ten years worth of old problem sets and homework assignments.

As my friend, John Morrow, at the University of Wisconsin, Madison puts it…

The current status of graduate programs seems to be that some students, notably those from countries where solution manuals and entire texts are copied as a matter of habit (generally out of necessity) have access to solution manuals. Incentives are clearly not to share them, since grades are often based upon homework covered by manuals. Given that this seems to be the case most places, failing to help distribute manuals known to be in circulation penalizes the just and rewards the wicked….It is also my impression that most students that visit this site, or at least the ones I have corresponded with, are interested in self-study for department examinations, etc. If one is trying to cover 100+ involved problems in a month to prepare for a test, a student without access to a solution manual is at a huge disadvantage to one who has access to a manual.

I remember the frustration of spending hours on a problem, going down the wrong path when a simple check of the first step of a solution would have shown that my simple calculus mistake was the reason I had an illogical answer. I learned fairly quickly that many of the other students did not have the same inefficient time wasting study habits; if they were stumped for more then a half an hour on a problem they would just look at the trusty solutions manual for a hint and continue solving the problem afterwards. Also, some exam questions were straight from the book (unassigned problems) so the student with a solutions manual could do every problem in every chapter and be better prepared for exams in which the mean hovered around 40%. Those students were able to grade their work and spot errors that gave them a deeper understanding of the voluminous amounts of materiel you are expected to assimilate in a first year economics PhD program. It is a huge advantage to do as many problems as possible before a test to hone the problem solving acumen that got you into the program to begin with (you and everyone else in an economics PhD program).

Some friends of mine have speculated that maybe UV is trying to shake out a large first year class and have used this as an excuse to cut down the number of students. It is just unbelievable to think that the professors are so out of touch with reality that they don’t know solutions are photocopied in volumes every semester. Hell we had a professor give everybody full credit for our homework because everyone had the solutions manual anyways. I guess it could be possible that a naïve group of professors don’t know this goes on. A friend at Cornell pointed out that he couldn’t remember the last time a professor in a first year PhD program even graded an assignment? I know my TA’s graded damn near everything…I still have the unintelligible handwriting on my problem sets to prove it.

I don’t know anybody at the UV graduate economics department (I was accepted with a fellowship to attend the program and would have been in this years class had I had the inclination), but I would love to know the real reason for this controversy. Is it internal faculty politics? Naivety? Too many people passed the qualifying exam and the department wants to save money? If anyone knows, please email me.

What I am certain of is that, based on the information available so far, nearly every student in every graduate level economics department is guilty of cheating. Could it really be that having a copy of the solutions manual really cheating? Damn!

Update: It has been brought to my attention that the University of Virginia is usually referred to as UVA (not UV as I posted). Ooooops!

Update II: Ian writes in comments a post that deserves to see the light of day…

Glad to see you post something on this Chris. As you know, I think this is a very bizarre move on the part of the UVA econ department. I would think that a program like UVA, which I understand to be rather competitive in the first year, it would be preferable to ensure that students not gain an edge over each other by the accident of access to information. I suppose kicking students out for “cheating” is one way to do that, but of course all it means is that the people who have the materials will just do a better job of hiding them from one another. If solution manuals are outlawed, only outlaws will have solution manuals. The other way to remove the advantage conferred by having the solutions is to make them available to all students.
This is why it is incumbent upon graduate students to make old class materials as widely available as possible. First, it is the ‘fair’ thing to do, since it restores the balance of competition within departments (not to open a debate on the notion of ‘equality of opportunity’). From a practical standpoint, if graduate students are ‘out’ about sharing old course materials and solutions it forces administrators to acknowledge the issue early on. At the very least it makes it harder for them to pretend ignorance of the practice at the end of the year.
John Morrow deserves a great deal of credit for getting this information out there. I hope to do something similar for the incoming class at Cornell, and would like to open a dialogue with our DGS on this topic. Of course, there are always copyright issues to worry about. Mr. Morrow could speak more to these than I, since his website seems to have drawn some fire from publishers. Maybe it’s time for econ grad students to begin a grand project of ‘open source’ solutions. We wouldn’t have to worry about copyright violations, and they would probably be better than some of the terrible (and often wrong) solutions in the official publications (not that I’ve ever seen them, of course; I’ve just heard).

Update III: Crowebar has more here.

This just doesn’t add up.

Wait…lemme check the answers to make sure….

nope…this just doesn’t add up.

Update IV: Steven Levitt writes…

A few things surprise me about this article.

First, when I was in grad school, no one cared how you did on problem sets. They had nothing to do with your final grade. I got a “check minus” on every problem set in the most important fall quarter class the first year (Frank Fisher’s micro class), but I got an A in the class. Of all the things to cheat on, problem sets would be at the bottom of my list.

Second, I wonder how the professor didn’t notice. Either the students were creative, or the problems must have been pretty easy, so a lot of right answers weren’t surprising. At MIT and Chicago, I feel like hardly anyone ever gets
a completely right answer to anything.

Does the honor code apply to professors? If, say, a professor pretended to grade some undergraduate papers, but really a grad student did it, would the only choice be that the professor gets expelled?

an annonymous commenter writes that…

The problem sets are what the papers are focusing on but they are not what is being focused on here at UVa. Somewhere between 3 and 9 students are suspected of cheating on the prelims which is what started the whole thing.

This would make more sense to me.