Questions tagged [mathematical-economics]

The application of mathematical methods to represent theories and analyze problems in economics.

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17 views

Interpretation of dummy variable : Random Effects Model

I am running a RE regression and I have export similarity index between two countries as the dependent variable and have a dummy variable such as share a border(=1 if countries share border, 0 ...
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27 views

Why decreasing co-state variable (over time) is Compulsory?

I have a short question. In the continuous time infinite horizon optimal control maximization problem Like $$\max \int^{\infty}_0 u(c_t)e^{-pt}dt$$ I use current hamiltonian function and I obtain ...
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38 views

What is the economic interpretation of the solution of this optimal control problem?

I have the following optimal control problem $$\max_{c_t} \int^{\infty}_0 e^{-p_it}\ln(c_t(i))dt$$ subject to $$\dot{w_t}(i)=rw_t(i) -n_ic_t(i)$$ $$w_0(i)=w_0>0$$ I have some wealthy and ...
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39 views

How to find mixed optimal strategies in this zero-sum game?

I'm trying to solve this problem from last year final exam in game theory: Consider the zero-sum game $G=(X, Y, g)$ where $X=Y=[0,1]$, and $$\forall (x,y) \in X \times Y: g(x, y)=\max \{x(1-2 y), y(...
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1answer
18 views

Is there some definition about risk sharing?

I was searching for a definition of risk sharing and I have found the following: $\underline{Definition:}$ Risk Sharing — also known as "risk distribution," risk sharing means that the premiums and ...
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12 views

New equilibrium when ad-valorem tax is imposed on supplier [closed]

In a question in a past final from my intro Microeconomics courses we're given the following demand and supply equations: $P_s=50-\frac Q2$ $P_d=\frac Q2$ Which give an initial equilibrium quantity ...
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2answers
32 views

What is wrong with the idea that resource depletion causes recessions? [closed]

How can you refute this theory, such that it never comes up again.
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1answer
29 views

Dimensional analysis of GDP

The GDP is sometimes given by $$ GDP=P\cdot h\cdot e \cdot F $$ Where $P$ is the Productivity, $h$ is the number of hours worked, $e$ is the employment rate and $F$ is the size of the labor force. ...
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1answer
45 views

Interpretation of $\frac{\partial }{\partial p_1}Q_1(p_1, p_2)/\frac{\partial}{\partial p_2} Q_1(p_1, p_2)$

I am interested in an economic interpretation for the ratio of partial derivatives of a demand function $Q_1(p_1, p_2)$, which is \begin{equation} t=\frac{\frac{\partial}{\partial p_1}Q_1(p_1, p_2)}{\...
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57 views

Writing constraint

A firm accumulates useful knowledge $k$ by investing in R&D activities. Specifically, if the firm invests $r > 0$ dollars into R&D, the stock of useful knowledge grows by about $2\sqrt{r}$ ...
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1answer
53 views

Can we have a Non-Reflexive Preference Relation?

I've been thinking about preferences alot recently and have been specifically thinking about the reflexivity requirement. That is: $$x \succsim x$$ Though this is apparent and obvious, I have been ...
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44 views

Finding optimal path in continuous time

I have the following optimal control problem $$\max_{c_t,l_t} \int_0^{\infty} [ln(c_t)+\theta ln(1-l_t)]e^{-pt}dt$$ st. $$\dot{k_t}=k_t^{1/2}l_t^{1/2}-c_t-\beta l_t$$ $$k_0>0$$ I do big part of ...
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2answers
36 views

How to use an instrumental variable to estimate the parameter?

I have the following linear model of log wages (w) explained using years of schooling (S), years of experience and its square $(E,E^2)$ and 3 dummy variables indicating whether the individual was ...
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69 views

Bliss point hamiltonian function

I have the following utility function $$u(c_t)=g(c_t-b)^2$$ for constants $g,b>0$ Edited: in order to be bliss utility function, It must be g is negative. But in the question g is given to be ...
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1answer
34 views

Linear Probability Model Instead of Logit in Fixed Effects Regression

In our panel data analysis we estimated a fixed effects linear probability model (LPM) instead of a fixed effects logit regression because our sample size was quite small (600 individuals) and the ...
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1answer
73 views

Present value heuristics problem

No idea if this is the right stackexchange for this, feel free to point me elsewhere! I'm teaching business calculus and one of the problems the students have is to figure out the present value of a ...
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1answer
24 views

Consumption Set in Arrow-Debreu

I'm very inexperienced in mathematical economics, so when I came across the idea of the consumption set in Arrow-Debreu, I was a little confused. So for each element x in consumption set X, what does ...
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1answer
33 views

How to show that the estimator is consistent?

$Y_i=\beta_0+\beta_1X_i+U_i$ is my regression model for an I.I.D. sample with N=1000 observations. Suppose $U_i\sim I.I.D.(0,\sigma^2)$ and Xi are also I.I.D for i=1,2,3......1000. Xi is independent ...
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1answer
41 views

How to test if the effect of one regressor entirely comes from other regressors?

I have a regression model that includes IQ test scores as the dependent variable; my own education, my father's education and my mother's education as independent variables. Suppose I want to know ...
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16 views

Total factor productivity persistence [closed]

Would it make a difference whether a decrease in total factor productivity z on the labor, goods, and money market is persistent? (That is, whether decreased productivity today also is predictive of ...
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1answer
79 views

Linear Utility?

Consider a preference relation $\succeq$ on $X\subseteq\mathbb R^2$. If $\succeq$ satisifies: $$ \begin{align} &1.\mbox{ }(a_1,a_2)\succeq (b_1,b_2)\implies(a_1+t,a_2+s)\succeq (b_1+t,b_2+s),\...
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1answer
91 views

Dynamic programming, optimal consumption-savings (finite horizon) problem

Let $w_t$ denote a consumer's wealth at time $t$ and $c_t$, the amount she chooses to consume, so her savings exiting this time period are $w_t-c_t$. Given this savings decision, her savings $w_{t+1}$ ...
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0answers
77 views

What is Economic Interpretation of three nonlinear equations?

I have the following nonlinear system $w$ is wealth $c$ is consumption $r(w)$ is gross return on wealth $a,b, d$ are parameters which are strictly positive and fixed. $$\dot{w} =r(w)w-c$$ $$\...
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1answer
34 views

The assumptions of Rational Expectations Models

What are the assumptions between rational expectations models and how restricted are there for the following results of economic theory? Where can I find them all gathered in some textbook or in the ...
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1answer
40 views

Regarding the Expenditure Function Underlying a Bliss Point

I've been looking at expenditure systems and have been really interested in the behaviour of the demand system that underlies bliss points: Consider the bliss point utility function of the following ...
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25 views

Software used for solving demands of different functions

I'm currently doing some research on demand systems and have been experimenting with different underlying utility functions which will generate different systems of demands. However I've been doing ...
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31 views

Two different definitions for a Complete Relation

Many sources show this definition for completeness of a relation $$ \forall a, b \in A, a \neq b, (aRb) \text{ or } (bRa) \tag{1} $$ Others show only $$ \forall a, b \in A, (aRb) \text{ or } (bRa) \...
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5answers
648 views

Is it possible to have a preference relation that is complete but not transitive?

I've been doing my own reading on non-rational preference relations. Im currently under the impression that transitivity follows as a direct result of completeness of preferences. However my (much ...
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52 views

Existence of symmetric trembling hand perfect equilibria

Consider symmetric and finite game. By Nash (1950), the game must have at least one symmetric equilibrium (proof). Also, it must have at least one trembling hand perfect equilibrium (proof). ...
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2answers
106 views

Optimal Production Input in Relation to Cost Minimization Problem

I was doing my homework and got really confused about how to approach the optimal levels of inputs when there are three variables. My current understanding is that the problem is to solve the ...
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1answer
56 views

Regular annual pension

I am supposed to solve the problem: A 24-year-old man decides to invest 200,000 euros at a 7% annual interest rate to bring him a regular annual pension from 31 to 50 years inclusive. What will be ...
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1answer
44 views

Short cuts to solve Cobb Douglas Utility function (minimization)

Say a Cobb Douglas like: $$\max_{X,Y\: s.t. X \cdot P_x+ Y \cdot P_y=I} U=X^\alpha Y^\beta$$ When it comes to maximization I would do the following way (for the fastest result): x: $\alpha/(\alpha +...
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79 views

Revenue maximization problem

There are $N>0$ Households in an economy. The government has aim to maximize a weighted average of income by imposing tax on the rich people and redistribute the tax revenue to the labor ones. ...
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28 views

The centralized shift from barter to currency economy

Suppose some ancient king of small bronze age city-state wants to introduce universal currency instead of barter that is currently in overwhelming practice in his kingdom. In order to smooth the shift,...
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9 views

Overlapping Generations Model Pension System Question

Part 1 Pension System OLG Model with pension system: Each individual lives up to two periods. The surviving probability at period 2 is p. At period 1, the young household consumes c1, saves s1, and ...
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2answers
111 views

Algebraic approach towards convexity

I have a function: $ u(x) = x_{1} + x_{2} + \min\{x_{1}, x_{2}\}$. How do we algebraically show if it's convex or not? Also, what would be the general way to show if any given function is convex.
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1answer
74 views

Central bank loss function (I did a solution, but it doesn’t totally make sense I guess)

I have question on central bank loss function. We know that the central bank loss function is $$L(\pi, \bar{Y})= (\pi- \pi^e)^2+\beta \bar {Y}^2$$ And we know that fisher equation is $$i=r+\pi^e$$...
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41 views

derive value function from utility function

We have the utility function. $$U_{t} = \ln{c_{t}} + E_{t}\sum_{s=1}^{\infty}(\beta^{s}\ln{c_{t+s}})$$ And I am trying to find the value function. $U$ is utility function. $c_t$ is consumption at ...
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0answers
46 views

Elasticity of substitution

So, this is an economics question but the problem I have is a pure math problem I guess. So I have the following equation:f(x,y) this function have the elasticity of substitution(EOS): 1/(1-beta). a,...
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1answer
36 views

What guarantees that endowed agents have non-zero prices in an Arrow-Debreu Economy

In my research I am trying to find minimal conditions to guarantee a quasi-equilibrium must always be a typical Arrow-Debreu equilibria in a rather specific production setting. This may be rather ...
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1answer
55 views

Prove that the set $X = \{x \in R^L_+| u(x) \geq \bar u\}$ is closed

Prove that the set $X = \{x \in R^L_+| u(x) \geq \bar u\}$ is closed. Saw this statement in the textbook but I'm not sure how this is the case when we don't have any restrictions on $u(x)$ such as ...
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1answer
48 views

Adverse selection problem

The classic literature refers to the problem where information asymmetry exists between an informed and an uninformed counterpart as the adverse selection problem, but how can we verify what kind of ...
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0answers
39 views

Quasilinear utility: if $x \succeq y - ae_1$, does it mean $x + ae_1 \succeq y$?

Quasilinear preference is defined to be: $x \sim y \Rightarrow x+ae_1 \sim y+ae_1$ and $x + ae_1 \succ x$ with $e_1 = (1,0,0,...)$, Given a quasilinear preference, if f $x \succeq y - ae_1$, does ...
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1answer
69 views

Supporting Hyperplane Theorem and quasiconcave utility function

My notes says that if $u(.)$ is strictly quasiconcave and differentiable, by the supporting hyperplane theorem, there exists $p >>0$ and $w \geq 0$ such that $ x = x(p,w)$ $\forall x$. I am ...
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50 views

Neoclassical Economic Growth Model Shadow Price for Discrete vs Continuous Time

I recently learned about the neoclassical growth model in both discrete and continuous time. The intuitive meaning of the shadow price for both cases is that it represents the value of one additional ...
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21 views

What is the the return to scale of per capita production function?

If $Y=f(AL,K)$ is CRS, $a_k+a_L=1$ by the Euler Theorem. However, I wanted to know the return to scale of $y=f(1,k)$ (i.e. $Y$ divided by $AL$). I tried $z=p/AL$ , then $py=f(p,pk)$, differentiate w....
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16 views

Questions regarding 'Efficient Trade with Interdependent Values' by Marek Pycia and Peng Wang,2015

This question is with reference to the paper 'Efficient Trade with Interdependent Values' by Marek Pycia and Peng Wang,2015(See here). At page no. 4 of the paper, the authors describe $v_i$ as the ...
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26 views

Modeling risk aversion. Expected utility function

I want to model an Expected Utility Function for risk aversion but my problem is uncertainty in itself. I want a function(a special case) $$f(x, y) =\left\{\begin{matrix} h(bx^{1-C}+ay^{1-C}),C\neq 1\...
4
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2answers
87 views

Set Theory Properties of the Budget Constraint

In Microeconomic theory, the budget constraint is defined by 4 distinct properties: It is Bounded Closed Convex Non-empty The 1. 2. and 4. are very straight forward and the benefits in terms of ...
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1answer
38 views

Why do the income and substitution effects cancel for log preferences? Trouble reconciling Slutsky decomposition

I've read (pg 10) in Gourinchas' notes on consumption that the income and substitution effects cancel for log preferences, and I tried to prove this to myself doing the Slutsky decomposition for the ...