Statistics Definition and 998 Threads

Homework Statement A random sample of 30 rats has 18 females and 12 males. If last year's proportion of females treated was 0.65, do the above data confirm that this year the proportion of females is different than last year? Homework Equations p = treated / total If using standard...

Homework Statement Suppose the porosity (in %) of samples taken from the ground found to be normally distributed with σ = 0.85 % What sample size is necessary to estimate the true mean porosity to within 0.25 with 99% confidence? Homework Equations C.I. = confidence interval =...

(Not sure if I should have posted this in the h/w problem section since it's not really hw...just a problem I've faced recently. But if it should be there, I can move it there. ) There are 5 boxes. Each box may contain a certain amount of marbles (1, 2, 3 etc.) and some have no marbles at...

At what age do babies learn to crawl? Does it depend on the time of the year that babies were born. Data were collected from parents who brought their babies into the University of Denver’s Infant Study Center to participate in one of a number of experiments between 1988 and 1991. Parents...

Suppose I have a regular quarter and I had to guess heads or tails. I have a 50% chance of getting heads or tails. After I flip it say I get the result: heads. If it is to be flipped a second time, classically I would say I still have a 50% chance pf getting heads or tails. However, from...

Can statistics be beautiful? http://news.bbc.co.uk/today/hi/today/newsid_8070000/8070108.stm

Hello, Is the relation between the PDF and CDF of order statistics is as any PDF and CDF. i.e.: F_X(x)=\int_{-\infty}^{x}f_X(t)\,dt Regards

Homework Statement A lie detector shows a positive reading 10% of the time given that the person is telling the truth and 95% given the person is lying. Suppose that there is a suspect who is denying the the crime and there is a 50% chance that the person comitted the crime. A. what is the...

Homework Statement There is a group of four blood donors: A, B, C and D. Only A has type A+ blood. Four blood samples, one from each individual, will be typed in random order until an A+ individual is identified. Let Y = {number of typings necessary to identify an A+ individual}. Compute...

Homework Statement The security passes for a certain company are coloured yellow or white, they're provided with either a clip or a chain. The probability that a pass has a clip is 6/10, 2/3 of the white passes and 4/7 of the yellow ones are fitted with clips. A member of the company is...

I am an instructor in a DOD academy. I am trying to show that the way that students are being graded in a particular performance test is a statistical improbability. I have 200 students, all of which received a final grade of A in a course which consisted of 38 performance tests. These...

Homework Statement Given a simple linear model y = B1 + B2*x + e and the least square estimators, we can estimate E(y) for any value of x = x0 as Y0 = b1 + b2*x0 Describe the difference between predicting y0 and estimating E(y0) Homework Equations The Attempt at a Solution I am not sure what...

Statistics Question - Normal Distribution SOLVED Homework Statement Hey, the question is shown in the attached document. Homework Equations Mean = 79 Standard Deviation = 12 The Attempt at a Solution I dispise these questions, and I'm failing to grasp them at all. I've done...

Can anyone give me an example of when a statistic is insufficient, using the factorization theorem, if possible? Thanks.

Homework Statement http://www.geocities.com/asdfasdf23135/stat15.JPG I am OK with part a, but I am having some troubles with part b. Homework Equations Width of a Confidence Interval The Attempt at a Solution Attempt for part b: http://www.geocities.com/asdfasdf23135/stat16.JPG...

I've been reading on this forum that Condensed Matter is the largest field of Physics. I can't find any stats of this anywhere. I've searched AIP.org numerous times and uncover nothing. It shows what skills and general jobs of various graduates, but nothing about specific fields. Can someone...

In statistics I learned how to do this problem one way, & in discrete mathematics I learned how to do it another way, but the answers don't jive. So I'm wondering if I'm doing something wrong. Below is the question. A bakery produces six different kinds of pastry. If the different kinds of...

Which is harder/more time-consuming in college? GPA killer?

Applied Math? vs. Statistics? vs. Computer Science? First of all, I enjoy all of these, and was wondering which you would pick based on other factors... Which one will have the most job opportunities in the near future (10 years approx)? Which one will have the most chances for lucrative...

Homework Statement Please can someone help me with this question, I am really stuck. I have drawn a tree diagram but I don't think it is correct, as it does not give the right answer. Can someone have a look at it and show me were I have gone wrong? Or show me what the tree diagram should...

Homework Statement I've been trying, with no success, for the past few hours to find a way to keep calculations done in the TI-89's "Stats/List Editor" in exact form instead of decimal. For example, when I enter the following information: http://img19.imageshack.us/img19/4061/prob1y.jpg...

Homework Statement Hi there: I just need someone to tell me if I've made a mistake somewhere in my solution to this: Suppose that X1 , . . . , X2n+1 are i.i.d. random variables that form a random sample from the U (0, 1) distribution. Suppose that the values are arranged in increasing...

Homework Statement You've got N marbles, and N bins. one by one, a marble is randomly placed in a bin. What is the probability that there will be no marbles in a given bin. Homework Equations P=N!/(n1!n2!)*p^n1*q^n2 : binomial probability The Attempt at a Solution since we're...

Are there any statistics on PHD doctorants whose thesis was on beyond the standard model, I mean how many percentage of them got to keep working in this field after they got their PHD?

How many permutations can be made out of the letters of the word STATISTICS?

[b]1. Polotical parties rely heavily upon polling to measure their supports in the electorate. Below are the results of a poll conducted in 1996 for four (i only listed the one needed) political parties. Level Count Probability Stderr Prob N 250...

Problem: Let Y1,Y2,...,Yn denote a random sample from the uniform distribution over the interval (0,theta). Show that Y(n)=max(Y1,Y2,...,Yn) is a sufficient statistic for theta by the factorization theorem. Solution: http://www.geocities.com/asdfasdf23135/stat10.JPG 1) While I...

Homework Statement Q1) Theorem: An asymptotically unbiased estimator 'theta hat' for 'theta' is a consistent estimator of 'theta' IF lim Var(theta hat) = 0 n->inf Now my question is, if the limit is NOT zero, can we conclude that the estimator is NOT consistent? (i.e. is the theorem...

1) Theorem: An asymptotically unbiased estimator 'theta hat' for 'theta' is a consistent estimator of 'theta' IF lim Var(theta hat) = 0 n->inf Now my question is, if the limit is NOT zero, can we conclude that the estimator is NOT consistent? (i.e. is the theorem actually "if and only...

Homework Statement Q1) About "order statistics", sometimes it's denoted x(1) and sometimes it's denoted X(1). What is the difference between the two? Also, for X(1)=min{X1,X2,...,Xn}, it's a random variable. What does it mean to be the minimum of a bunch of random variables? If they are...

Hi, I'm a bit stuck on this problem A basketball player misses 30% of his free throws. He ends up in a situation where he has the potential to shoot two penalty shots if and only if he lands the first shot (called a one and one, I believe). The outcome of the 2nd shot is independent of the...

Studying for an intro course test and I have no one to compare it to right now.. any help would be appreciated. Here is the question. Q. Suppose X and Y are random variables such that p(X,Y)=1/3, Var(X) = 9 and Var(Y) = 1. Compute Var(X-2Y). Since X and Y are not independent, we are...

Studying for an intro course test and I have no one to compare it to right now.. any help would be appreciated. Here is the question. Q. Suppose X and Y are random variables such that p(X,Y)=1/3, Var(X) = 9 and Var(Y) = 1. Compute Var(X-2Y). Since X and Y are not independent, we are...

the heights of adult men at Suny Rockland have mean heights of 63.6 and a standard deviation of 2.5. What does Chebyshev's theorem tell us about the percentage of men whose heights are between 58.6 in. and 68.6 in.?

Hi. i keep finding a different answer than what textbook offers. is my answer correct? question: the quality control department of a company making computer chips knows that 2% of the chips arw defective. use the nurmal approximation to the binomial probability distribution, with a continuity...

Three random variables are generated X1, X2, X3 on a spnning fair wheel three times. these variables are independent and uniformaly distributes on [0,1]. find probability that these values are none within +-d of each other where 0<=Y1<=Y2<=Y3<=1 is order statistics for randon variables...

Hello, Suppose that we have N independent and identically distributed Random Variables (RVs) say X_1, X_2, \ldots, X_N. Suppose then that we arrange these RVs in magnitude and in an ascending order as X_{(1)}\leq X_{(2)}\leq \dots \leq X_{(N)}. Now, the question is: what is the probability...

Homework Statement Estimate the probability that, in a group of five people, at least two of them have the same zodiacal sign. (There are 12 zodiacal signs; assume that each sign is equally likely for any person.) Homework Equations P(X=k) = nCk * p^{k} * (1-p)^k{} The Attempt at a...

Homework Statement Hi all. I thought about this earlier today. Let's say I toss a dice three times, and the outcome is 2, 4 and 5. Is the mean (2+4+5)/3 or (2+4+5)/6? The reason why I am asking is that we can look at the mean as a weighted average of the probability of getting each...

Homework Statement From the data: x=-5 -4 -3 -2 -1 0 1 2 3 4 5 y= 1 5 4 7 10 8 9 13 14 13 18 These values are in a table, ie -5 corresponds to 1, -4 to 5 and so on. I have to find: Sxx=Sum of [x(i) - mean of x]^2 Sxy=Sum of [x(i) - mean of x][y(i) - mean of y] Im...

Homework Statement Hi all. Lets say I have two variables yk and xk. I also have two mean values given by: <y_k^2> = \frac{1}{N}\sum_1^N{y_k^2} \quad \text{and} \quad <x_k^4> = \frac{1}{N}\sum_1^N{x_k^4}. Now I am looking at the expression (<xk4> <yk2>)1/2. Question: Is it correct that...

Homework Statement I have a table with a data set #, and 2 variables (W and P) with values in the table. Homework Equations The equation (which I don't know what it means) says V= (summation with n on top and i=1 below Wi X Pi)/(summation with n on top and i=1 on bottom X Pi) The...

"If X is non-negative, then E(X) = Integral(0 to infinity) of (1-F(x))dx, where F(x) is the cumulative distribution function of X." ============================ First of all, does X have to be a continuous random variable here? Or will the above result hold for both continuous and...

Homework Statement Hi all. At a poll in America, where 1000 people have been asked, 480 people said that they would vote yes on proposition A (it is a fictive proposition), and of course 520 people said they would vote no on proposition A. I have to find the probability that proposition A...

Hey folks, I need a good intro to statistics book that will take me through the 'statistics equivalent' of a Cal I, II and III course (US). One that starts with a good foundation, and proceeds up to a pretty advanced level. I have just finished a PhD in physics, so my math is 'good', but...

Homework Statement Suppose the random variable X has a N(5,25) dsitribution and Y has a N(2,16) distribution and that X and Y are independent. Find a random variable F that is a function of both X and Y such that F has a F-distribution with parameters (1,2), i.e. F(1,2). Homework...

I had a MCQ exam today. 90 Questions with 4 alternatives. I need help calculating my chances of passing (which should be really small). I know 3 of my answers are correct. I gambled on the rest. Also, please calculate the chance of passing, assuming that my guesses were a little more...

If I flip two coins at once and don't care which one is heads in the case of a head and a tail, how many degrees of freedom are there?