Questions tagged [linear-algebra]

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How can I represent this observation regarding options in a formula?

By observing how an option's expiration P/L changes as its underlying asset price changes, we can discover the following system of equations: $\begin{cases}S_{Long} = C_{Long} + P_{Short} \\ S_{Short} ...
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2answers
53 views

What are the concepts in Linear Algebra that model the idea of Identification Strategy in Econometrics?

I just would like to know what concepts one should know before talking about identification strategies in econometrics. I see people studying such concepts but I'm not sure they realize (or even know) ...
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1answer
43 views

$x\sim y$ implies $x+a\sim y+a$ for any $a\geq0$ and $x,y\in\mathbb R^n$, then the preference is linear?

$x,y,a$ are vectors in $\mathbb R^n$ We say $a\geq0$ if all directions of the vector $a$ is greater or equal to zero. We want to prove (or disprove by counterexample) that: Suppose $x\sim y$ ...
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1answer
29 views

Derive the growth rate of an equation

I have the following equation: $$\mu =\left [s_{\pi }-v(s_{\pi }-s_{W})+\zeta \right ]$$ And I have to derive its growth rate, which is: $$\dot \mu =-\frac{v}{\mu } (s_{\pi }-s_{W})\dot v$$ Do ...
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1answer
24 views

Hep with total differentiation of an AD function [closed]

Is there anyone who can help me with a total differentiation exercize. I am starting with the following formula for AD: $$x=\mu ^{-1}(g+i+e)$$ Where $\mu$ is the Keynesian multiplier. And have to ...
6
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1answer
114 views

Econ Intuition for Jacobian inverse in demand system

Consider the following simple linear demand system (in vector notation) with n different products Demand: $\quad\mathbf{q=B\left(a-p\right)}$ Inverse demand: $\quad\mathbf{p=a-B^{-1}q}$ where $\...
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1answer
255 views

Calculating the elasticity of substitution between factors of production

Following the work of Lu (1967) (Full text available here!) I got stuck trying to derive the elasticity of substitution between factors. He use the formula developed by Allen, that when the production ...
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1answer
229 views

How to utilize the projection matrix in econometrics?

When consider the following DGP : $y=X\beta^{*}+\epsilon$ where $\beta^{*}$ is a $\tilde k\times1\ $ vector. Define the projection matrices: $P_{X}=X(X^{T}X)^{-1}X^{T}$ and $M_{X}=I-X(X^{T}X)^{-1}$. ...
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1answer
178 views

Has this differential calculus inequality approach to optimizing the production possibility curve exist?

I just started micro-economics at my community college and my teacher mentioned the derivative of the PPF for two output resources. I thought about it a while and came up with this approach. Some of ...
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84 views

Visualising eigenvectors/values

This might seem like an odd question but seeing as I haven't had any formal education in solving ratex models yet, it is something I have been thinking about a lot recently. Consider the following ...
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2answers
159 views

Budget hyperplane in n dimensions

Take the set of all vectors $x = (x_1, \cdots, x_n)$ that are solutions to $p_1x_1 + \cdots + p_nx_n = I > 0$. Show that this set has $n-1$ dimensions. I have somehow managed to get myself ...
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1answer
390 views

When gradient of utility function is a zero vector

In Advanced Microeconomic theory by Jehle and Reny is said that if $\mathbf{x^*}$ is a solution to the following maximization problem $\max_{\mathbf{x} \in \mathbb{R}_+^n} u(\mathbf{x}) $ subject to $...
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0answers
486 views

Short Run vs Long Run Cost Functions

Let $z_a$ and $z_b$ are two vectors of inputs. $z_a$ is variable in both long run and short run however $z_b$ is only variable in long run. Now let's suppose that the price of one of the inputs in ...
6
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3answers
248 views

How to deal with a singular Leontiev inverted matrix?

I am currently studying and experimenting the input-output methodology. It is a 1930's method based on national accountings that allows to measure the interindustry flow of good and services. ...
3
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1answer
56 views

How can I write a conditional expectation of finite state markov process in matrix notation

NOTE: This question is related to the econometric method explored in the following two questions: Multiplicative factorization of stochastic growth time series--solving for an eigenfunction/...