Friday, March 11, 2011

Books to Read 4- Fundamental Methods of Mathematical Economics


The forth book which a prospective graduate student in economics is expected to have read is

Fundamental Methods of Mathematical Economics by A C Chiang
As mathematics is being increasingly used in economics it’s quite necessary for the students to be familiar with basic and advanced mathematical techniques in Linear Algebra, Calculus, Probability and other important mathematical areas.
This book serves the purpose very well. It’s better to be able to solve the problems at the end of the each chapter such that you know that you understand the concept. The books may take quite some time to finish but it’s worth spending time to understand the book completely.
With this book, readers can use another book
Schaum’s series of mathematical Economics
The beauty of Schaum series book is that it’s written very lucidly with several examples from economics which makes you understand the application of mathematical techniques in economics. In fact… if you don’t have enough time and you want to understand the necessary basic mathematical techniques for economics, probably this is the book.

Friday, March 4, 2011

Admission Results Out

Hi All,

Most of you have been waiting for admission results for last couple of days now. The admission results of universities are being declared so watch your mails and check your admission status online. A few universities which have declared admission results are

SUNY Buffalo
Kansas State University
Georgetown University
Emory University
Northwestern University
University of Michigan Ann Arbor
University of Maryland
Washington University
Boston College
New York University

Though best of my knowledge these universities have declared admission decisions, applicants must verify them. This post is simply to inform that results are being declared. Some of you might have accepted, some rejected and some may be on wait-list. If you are on wait-list, don't hesitate to write email to graduate director of your program about your status and if you are really interested in the program let them know. You can try to increase your chances of admission and assistantship by contacting them now.

All the best!!!





Saturday, February 19, 2011

BTR 3 - Basic Econometrics by D. N. Gujarati


The third book in the series is
Basic Econometrics by D. N. Gujarati
This book is also very easy to understand book. Before reading this book all you need to know is simple statistics. Any basic level of statistics would be good in order to comprehend this book. Some advanced statistical techniques that a reader may not have had in his basic course on statistics but are needed to comprehend the book thoroughly; has been provided in the Appendix of the book.
The book contains all the basic necessary econometrics concepts in order to prepare its readers for graduate level econometrics courses. As the name suggests it’s a basic econometrics book but it certainly does not leave out any important concepts. However more rigorous proofs may have been omitted sometimes.
The book begins with the introduction to econometrics and linear regression and proceeds to non-linear regression, time-series and econometric models. The book has several examples related to theories of economics. It also has a number of problems at the end of each chapter.
In all this is a nicely written book on basic econometrics and recommended for beginners.

Saturday, February 12, 2011

Decision of saying “I love you”: An economic interpretation


Valentine day special
Did you ever think that there can be an economic analysis of saying ‘I love you’ to a girl/guy? Well… here I’m trying to build up a model which determines the cases under which a girl/guy will say these magic words to a guy/girl.
Suppose that person ‘A' is going to say these magic words to person ‘B’ then ‘A’ can expect one of the two replies; either a ‘yes’ or a ‘no’.  Essentially the probabilities of any of these replies lie in the range of 0 to 1. The probability of ‘yes’ and ‘no’ depend upon the specific circumstances and are endogenous to the model following the fact that A can perform certain acts and put efforts in order to increase the probability of ‘yes’ and reduce the probability of ‘no’. Putting any effort on the part of ‘A’ is a cost to ‘A’. To simplify the calculation assume this cost to be zero. The probabilities of ‘yes’ and ‘no’ are known to ‘A’ and are ‘p’ and ‘1-p’ respectively.
Now assume that the payoff that A receives from a ‘yes’ is ‘H’ and the payoff from a ‘no’ is ‘-T-N’. The negative payoff from a ‘no’ can be separated into two different components. The payoff from not having B as his/her partner is (-T) and (-N) is negative payoff from a ‘no’ because, say his ego gets hurt.
Indeed we can expect H to be non-negative and T and N to be non-positive. A non-negative H implies that A is happy and gets some positive utility if he gets a ‘yes’ and certainly doesn’t get negative utility. Similarly, a non-positive T and N imply that ‘A’ gets negative utility if ‘no’ and in certain cases where ‘A’ is not at all affected by a ‘no’; T and N both are equal to zero.
‘A’ will then decide to say these magic words to ‘B’ if and only the expected payoff from saying these magic words is greater than or equal to from that of not saying these words. So we compute the expected payoff from saying these magic words
E (say) = pH + (1-p) (-T-N)
On the other hand, the expected payoff from not telling these words to B will be
E (don’t say) = (-T)
The right hand side of the above expression is simple to derive. If ‘A’ is not going to say these words to B; with probability 1 he gets no response and receives a payoff of (-T). Therefore, A will say these magic words to B if and only if
pH + (1-p) (-T-N) ≥ (-T)
or,                          pH –T –N + pT + pN ≥ (-T)
or,                          p (H+T+N) ≥ N
or,                          P ≥ {(N)}/(H+T+N)
Thus A will decide to say these magic words to B if the probability of a ‘yes’ is greater than or equal to the expression in the right hand side above. The equation suggests that value of ‘N’ is crucial.
Some interesting cases:
Case 1. When (-N) = 0;
Did you ever wonder there are guys who will say these words to each and every girl just at every possible opportunity? These are the guys who don’t worry at all about the negative response from the girl. In other words, for them (-N) as well as (-T) both are zero but since H is still positive, for them expected payoff from saying these words is always more than the expected payoff from otherwise.
Notice that even those who get negative payoff from not having the person as partner will say these words to their desired ones as long as a ‘no’ does not add to their negative payoff from not having the person as their partner, in equation form it’s just because the numerator (-N) is zero. So even if probability of a ‘yes’ is slightly positive or even zero that is, p=0; they will take the chance.
Case 2. There are people who can’t digest a ‘no’. For them to say these magic words, ‘p’ has to be very close to 1. In equation terms
                                N = H+T+N
Equivalently H is equal to (-T). Recall T has a negative sign.
Important points
Here we allow ‘p’ to be negative as well which is practically not possible however a negative ‘p’ should imply that A is going to say these magic words to B with certainty.
Examples,
A.      The ‘p’ can only be negative when H is greater than the sum of T and N. Since the numerator is always negative. This implies that positive payoff from a ‘yes’ is very large and hence A must convey these words to B. This is a result which one would arrive at intuitively.
B.      The second case pertains to the situation when absolute value of T is very large. What does intuition say in this particular case? Of course A should go ahead and tell this to B since the negative payoff from a ‘no’ is very large. The equation tells the same thing, if T is large enough compared to H in absolute sense, a smaller ‘p’ is needed to say these magic words.
In fact the difficulty in saying these magic words arises only when absolute value of N is very large compared to absolute values of H and T. This is also intuitive since those who are too egoistic or give much more value to social sanctions will go ahead only when they are almost sure about a ‘yes’. In this case ‘p’ will be near equal to 1 since we also expect H and T to be correlated. The more pleasure you get from getting the company of person, you also miss him/her badly.
So if you are mulling over whether or not you should tell these magic words to the person you love, calculate the probability with which you should tell her and compare it with the probability that you think he/she is going to give a positive response.
I would like to have your comments on this post.If you find some computational error please let me know. Thanks.