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by mahalekrishna
April 2nd, 2009, 10:12 pm
Forum: Brainteaser Forum
Topic: Prove that Y1 and Y2 are independent
Replies: 16
Views: 47788

Prove that Y1 and Y2 are independent

QuoteOriginally posted by: PdISince the event{X₁+X₂=y₁,X₁/(X1+X2)=y₂}is equivalent with the event{X₂=y₁(1-y&#8322,X₁=y₂y₁}we obtain for the densityf(y1,y2)=exp(-y1*(1-y2))*exp(-y1*y2) =exp(-y1)yikes.. you transformed the space (plane) without accounting for the jacobian
by mahalekrishna
April 2nd, 2009, 10:09 pm
Forum: Brainteaser Forum
Topic: Guard Dog's Area of Coverage
Replies: 3
Views: 42785

Guard Dog's Area of Coverage

<t>is there any catch in this one ?l>b; aba <=l <b; 0.5(a(l^2-a^2)^0.5 + l^2 taninv(a/(l^2-a^2)^0.5)) 0=< l <a; pi l^2/4 if the dog is tied outsidel>a+b; 0.25pi(3l^2+(l-a)^2 + (l-b)^2) - {donkeywork}; where donkeywork is the overlapping areab<=l<a+b; 0.25pi(3l^2+(l-a)^2 + (l-b)^2)a<=l<b; 0.25pi(3l^2...
by mahalekrishna
April 1st, 2009, 6:28 pm
Forum: Student Forum
Topic: Simple question on Brownian Motion.
Replies: 6
Views: 41569

Simple question on Brownian Motion.

<t>QuoteOriginally posted by: iliketopologyQuoteOriginally posted by: mahalekrishna okay, lets hav a look at this onelet m(t) = cX(t/c^2)X(t) - X(s) ~ N(0, t-s)... this is just definition (mere representation)hence, X(t/c^2) - X(s/c^2) ~ N(0, (t-s)/c^2).. for the moment lets assume c>0P((m(t)-m(s))<...
by mahalekrishna
April 1st, 2009, 6:15 pm
Forum: Student Forum
Topic: Log likelihood object in Eview
Replies: 0
Views: 40814

Log likelihood object in Eview

Hi,Anyone who has used the LogL object in EViews.. please share your file with your model (one that didnt work, the model i.e... the code needs to be working), for reference. I will be forever indebted.
by mahalekrishna
April 1st, 2009, 6:01 pm
Forum: Student Forum
Topic: Simple question on Brownian Motion.
Replies: 6
Views: 41569

Simple question on Brownian Motion.

<t>QuoteOriginally posted by: iliketopologyQuoteOriginally posted by: mahalekrishnai think it follows from definition X(t) - X(0) ~ N(0,t).. X(t/c^2) - X(0) ~ N(0,t/c^2), from here we can compute dP(cX(t/c^2) -cX(0) <=z)/dz (even this is not needed.. the specific corollary for normal variates can be...
by mahalekrishna
April 1st, 2009, 5:26 pm
Forum: Student Forum
Topic: Simple question on Brownian Motion.
Replies: 6
Views: 41569

Simple question on Brownian Motion.

i think it follows from definition X(t) - X(0) ~ N(0,t).. X(t/c^2) - X(0) ~ N(0,t/c^2), from here we can compute dP(cX(t/c^2) -cX(0) <=z)/dz (even this is not needed.. the specific corollary for normal variates can be used if eps~N(mu, sig^2) then k*eps~N(k*mu, (k*sig)^2) ))
by mahalekrishna
April 1st, 2009, 11:58 am
Forum: Student Forum
Topic: Marginal and Conditional density in options pricing
Replies: 3
Views: 41686

Marginal and Conditional density in options pricing

<t>I think marginal and conditional densities mean the same thing, they mean that we have to keep some variables constant and integrate the pdf wrt the other variables over the entire domain, something like P(-inf<x1<inf and -inf<x2<inf|x3=k3 and x4=k4), so we have marginal distribution as some func...
by mahalekrishna
April 1st, 2009, 11:39 am
Forum: Student Forum
Topic: Square-Root-Rule (VaR and Volatility)
Replies: 6
Views: 43921

Square-Root-Rule (VaR and Volatility)

<t>QuoteOriginally posted by: AlanTo answer your other post, the general motivation for the square-root ruleis an iid assumption. Suppose R(i), where R(i) is the simple return in period i is drawn independently each period from an identical distribution.Then, the final wealth after N periods is W(N)...
by mahalekrishna
March 31st, 2009, 3:30 am
Forum: Brainteaser Forum
Topic: Roll A Die Till You Get All Six
Replies: 16
Views: 51554

Roll A Die Till You Get All Six

<t>hi.. i have a way, but dont know whether it holds good (summable) for a hyper-dice (h). my way is fairly simple . Let mi be the probability of occurrence of the i-th side (std ritual: sum(mi)=1) and let the die-roll end in the r-th try with the k-th side. sigma(xi)=r-1 such that xi is N, xi>=1 fo...
by mahalekrishna
March 31st, 2009, 1:46 am
Forum: Brainteaser Forum
Topic: guess the highest number?
Replies: 5
Views: 44919

guess the highest number?

i can provide an amateurish view.. since the decision is conditional on knowing the rand no 'e' and the number on first card 'z0', for the argument to be true 'p(z>z0|e>z0)' should be meaningful, but i am unable to find any such meaning
by mahalekrishna
March 31st, 2009, 1:25 am
Forum: Brainteaser Forum
Topic: Prove that Y1 and Y2 are independent
Replies: 16
Views: 47788

Prove that Y1 and Y2 are independent

<t>i have a amateurish approach.. sadly i am an amateur actually the prob(y1<z1 and y2<z2)=p(z1&z2) can be calculated within the region bounded by x1, x2>=0, x1+x2<=z1 and x2>=(1/z2-1)x1, for the integrand exp(-x1-x2).This trivially reduces to p(z1&z2)=z2(1-exp(-z1)-z1exp(-z1)) for 0<=z2<=1 ...
by mahalekrishna
March 30th, 2009, 11:27 pm
Forum: Student Forum
Topic: Isnt the risk-neutrality condition absurd ?
Replies: 1
Views: 40947

Isnt the risk-neutrality condition absurd ?

I am a bit confused regarding this, most researchers have concentrated on better process specifications and many famous pricing formulae price assets using first moments.