Recent content by Phox

I'm trying to write some code to do a regression on data weight (x) and time (y). As best as I can tell, the model should be y = b1 + b2ln(x), but I don't know how you can do this by hand (I know how to in R...). I also know how to do a simple linear regression by hand. Can it be done using...

Ok, thanks. That makes sense. I normally just try to stay away from tables and use my ti-89 instead.For another problem, same concept: I'm testing B3 = 0 vs b3 =/= 0 at 5% level of significance. I found a test statistic of -1.516. tistat.tcdf(-∞, -1.516, 12) = .0777. Since it's two tailed I...

Homework Statement I'm looking through some example problems that my professor posted and this bit doesn't make sense How do you come up with the values underlined? Homework Equations The Attempt at a Solution Upon researching it, I find that you should use α/2 for both...

Homework Statement L(θ) = ∏(θ/(2√xi)*e^(-θ√xi)),i=1, n Homework Equations The Attempt at a Solution -> θ2∏(1/(2√xi)*e^(-θ√xi)) taking natural log of both sides lnL(θ) = nlnθ + ln∏(1/(2√xi)*e^(-θ√xi)) = nlnθ + Ʃln(1/(2√xi)*e^(-θ√xi)) Ok so from what I understand the...

's' represents the sample standard deviation. I'm still a bit unclear as to how we come up with the value 2.602

Ok. That makes sense. I suppose I'm confused because in the previous problem we were asked to find P(xbar >52) and we used z scores/normal cdf

Homework Statement Let X1, X2,...,X16 be a random sample of size 16 from N(μ=50, σ2=100) distribution. Find P(Xbar > 50 + .6505(s)) Homework Equations Z= (xbar - μ)/(σ/√n) The Attempt at a Solution So I know the solution of this problem is given by P( T(15 d.f.) > 2.602 )...

have I bounded the integral correctly?

Homework Statement Given joint pdf: f(x,y) = (2/(x2(x-1)))(y-(2x-1)/(x-1)) x>1, y>1 find marginal pdf fx(x) Homework Equations fx(x) = ∫f(x,y)dy, 0, ∞ The Attempt at a Solution fx(x) = ∫(2/(x2(x-1)))(y-(2x-1)/(x-1)) dy, 1, ∞ = [-2y(x/(1-x))/x3],1,∞ = undefined. stuck here

Homework Statement Let X1, X2,..., Xn be a random sample of size n from a geometric distribution for which p is the probability of success. Let m denote the sample mean. Use the method of moments to find a point estimate for p. Please write your answer in terms of m. Homework Equations The...

Homework Statement Suppose X and Y have the joint probability density function: f(x,y) = x+4y, 0<y<x<1 f(x,y) = 0 otherwise Find P(X>4Y) Homework Equations The Attempt at a Solution I'm not sure how to do this. I've already found marginal pdf's for x and y.. although I...

I've graphed it. I'm not sure what this tells me

Ok, so i guess the bounds of f1(x) were supposed to be from x to 1. And the bounds from f2(y) were supposed to be from 0 to y. But I don't don't understand why

Homework Statement Let X and Y be random variables of the continuous type having the join p.d.f.: f(x,y) = 8xy, 0<=x<=y<=1 Find the marginal pdf's of X. Write your answer in terms of x. Find the marginal pdf's of X. Write your answer in terms of x. Homework Equations The...

Thank you! I guess I'm not really sure how to use my z-score table correctly. I don't know how you get z1 and z2 to that many decimal places of accuracy