Statistics Definition and 998 Threads

If p(x) is a probability distribution on the real number line, the "wrapped" distribution around the unit circle is: p_w(\theta)=\sum_{n=-\infty}^\infty p(\theta+2\pi n) which is periodic with period 2π. The (differential) entropy is: H=-\int_\Gamma p_w(\theta)\ln[p_w(\theta)]\,d\theta where...

(solved) Calculate the standard deviation (statistics) Homework Statement From this table of values, I'm supposed to calculate the standard deviance Homework Equations Up until this point, I've had no problem calculating the standard deviance with my calculator by going to STAT>...

This is ridiculous. I couldn't decide where to post it, as it is a little bit about politics and a little bit about stastics, so there are reasons to post in other forums as well. It can be even a brain teaser (see the question at the end of the post). For those of you who don't know -...

Hello experts, Thanks to discussions with Stephen Tashi for getting me this far. See the problem statement in the attached PDF page 1. I need help solving for Qc in equation form, as a function of the other variables (N and C), preferably using erfc so I can program an accurate algorithm...

Homework Statement Suppose that X is normally distributed with mean 95 and standard deviation 17. A. What is the probability that is greater than 126.79? B. What value of X does only the top 16% exceed? Homework Equations z= (X-(mean of x))/standard deviation The...

Statistics, multiple choice, regression equation -- 2nd question Homework Statement A regression equation was developed to predict gasoline mileage (mpg) for various car weights (pounds). The resultant equation was: Y = 35.2 - .0034 X. Which two answers can be concluded? A. The...

Homework Statement The correlation coefficient for each of two data sets is calculated. Set A has r = -0.75 while Set B has r = +0.55. Which set (A or B) has the stronger strength of relationship? Homework Equations I think -0.75? The Attempt at a Solution I think Set A r =...

Statistics help -- Scatter plot, regression Homework Statement Consider the following data set for ten first grade students; the variables are the number of minutes spent learning a list of spelling words and the number wrong on the spelling test. [15 points total] (supposed to be a...

Homework Statement In a bilingual school there is a class of 21 pupils. In this class, 15 of the pupils speak spanish as their first language and 12 of these 15 pupils are Argentine. The other 6 pupils in the class speak english as their first language and 3 of these 6 pupils are argentine...

Homework Statement From January to September, the mean number of car accidents per month was 630. from Oct - Dec the mean was 810 accidents per month. What was the mean number of car accidents per month for the whole year? Homework Equations The Attempt at a Solution...

I've got three types of light: - star light - light from a discharge lamp - light from a laser emitted high above threshold and I need to decide on which type of counting statistics are expected for the detection of each source: poissonian, super poissonian or sub-poissonian. However, I'm unsure...

A new blood test has been shown to be effective in the early detection of a disease. The probability that the blood test correctly identifies someone with this disease is 0.99, and the probability that the blood test correctly identifies someone without that disease is 0.95. The incidence of...

Hi everyone, I've derived a formula which computes a certain quantity. This is the equation: f(x,t)=a(x,t)-\frac{1}{n}b(x)f(x,t)^{(1-n)/n}\frac{\partial f(x,t)}{\partial t} I need to prove that f(x,t)\sim a(x,t). All I have is that 0.5 < n < 2 , b(x) is a decreasing function of x...

Homework Statement Show that for identically distributed, but not necessarily independent random variables with positive pairwise correlation ρ, the variance of their average is ρσ^2 + (1-ρ)σ^2/B. ρ - pairwise corellation σ^2 - variance of each variable B - number of samples...

a congested computer network has a 0.002 probability of losing a data packet and packet losses are independent events. a lost packet must be resent. a) what is the probability that an e-mail with 100 packets will need any resent? i know the answer is P= 1-(1-0.002)^100 however i...

Homework Statement Let X1, X2, … be independent exponentially distributed stochastic variables with parameter λ. For the sum Y = X1 + X2 + … + XN, where N is a geometrically distributed stochastic variable with parameter p, show that Y is exponentially distributed with parameter pλ...

Homework Statement A touring ‘Blue Caps’ party of 20 cricketers consists of 9 batsmen, 8 bowlers and 3 wicket keepers. A team of 11 players must be chosen from the players such that there are at least 5 batsmen, 4 bowlers, and 1 wicket keeper. How many different teams can be selected? (a)...

Dear All, Recently I have published a paper on Bell's theorem ASTP 4(20) 945-949 (2010). One can also find it on arXiv as http://arxiv.org/abs/1012.4990. I am interested in a discussion about the results of the paper. The claim of the paper is that mathematically Bell's theorem is...

Now, I'm interested in all sorts of math, but currently I'm really liking statistics. However, I don't have any education in the subject at all. I was wondering if any of you knew a resource, say a book or a website, which could provide a comprehensive education in statistics and probability...

In my lecture notes on confidence intervals the lecturer wrote this: I don't understand the notation of that bolded text. I know X is a random variable, μ is the population mean and σ is the population standard deviation but what does the ~ mean? Also the N(μ, σ2) I assume means normal...

Homework Statement What is the age distribution of promotion-sensitive shoppers? A supermarket super shopper is defined as a shopper for whom at least 70% of the items purchased were on sale or purchased with a coupon. The following table is based on information taken from Trends in the...

Hello Everyone, My statistics is terribly rusty so I am turning to all of you for assistance! I am in the process of reviewing my old text but I figured this may be quite a bit quicker. Homework Statement Suppose "x" is normally distributed with "mu_1" and "sigma_1." Now suppose x is measured...

Homework Statement Two classes made a test. In one class there were 30 students, and the average score was 80. In the second class, the average score was 70. The average of both classes was 74. How many students were tested in the other class? Homework Equations The solution is 45...

Homework Statement Given 4 particles to be divided among 2 zones, one of 3 cells and one of 2 cells. For B-E statistics find W for each macrostate from N1=4, N2=0 to N1=0, N2=4, using both the formula and block diagram. Homework Equations The relevant equation is W=(g+Ni-1)!/(g-1)!Ni...

Homework Statement Find the critical value (or values) for the following and illustrate each using the Bell-Shaped Curve: Numerous example such as- 1) \alpha = 0.05, two-tailed test 2) \alpha = 0.01, left-tailed test 3) \alpha = 0.005, right-tailed testHomework Equations This is what I'm...

Hello all, Because of some schedule problems my summer semester can only fit 1 math course and I need some advice in deciding which one would be more useful. I'm a junior physics major with intents to attend graduate school in the Fall of 2012. Basically which one would be more useful in a...

Hello, As part of a research project I'm going to have to run some relatively (for me) advanced stats. Anybody know of a forum where I can post my stats questions? Thanks! Michael

Homework Statement The temperature reading from a thermocouple placed in a constant-temperature medium is normally distributed with a mean μ, the actual temperature of the medium, and standard deviation σ. What would the value of σ have to be to ensure that 95% of all readings are within 0.1...

Hi everyone, My data consists of road accidents and spatial covariates. Originally i wanted to apply an inhomogenous Poisson process with covariates. Then I realized that the accidents cannot occur everywhere in space, but only on roads. I found an example, that is quite similar to mine. it...

Hello Everyone, I was wondering if there is a statistical method to compare two linear equations. I have one "nominal" equation y1=a1*x+b1 and one equation found using linear regression on a data set, y2=a2*x+b2. I know I can just "look" and compare the slope and intercept values but it...

I'm a Chemistry major with Math minor. After graduation I want to work for a few years and go to grad school for a career change. Throughout my undergrad years I somehow lost interest in Chemistry and now like Math a lot better (courses such as Differential Eq, PDE). First thing that came to my...

We know that the particles in the hot universe obey Fermi/Bose statistics, but when we calculate the scalar dynamics i.e. in inflation or dark energy... and maybe also something else, it seems we don't take into account the statistics and just use one scalar field to calculate all these...

Let us consider the B-E and F-D statics: {<}{n}_{i}}{>}{=}{\frac{1}{{exp}{(}{{\epsilon}_{i}{-}{\mu}{)}{/}{kT}}{\mp}{1}} Now we observe the formula from a boosted frame.The left side is a scalar and should not change in response to the Lorentz transformations.What about the right hand side?The...

Homework Statement Let X1,...,Xn be independant Uniform(0,1) RVs. Find Cov(Xn,X(n)) when X(n) is the nth ordered statistic. Hint: Find the joint cdf of Xn and X(n) Homework Equations Cov(X,Y) = E[XY] - E[X]E[Y] The Attempt at a Solution I know that E[Xn] is 1/2 and that the...

Homework Statement I hope that I'm posting it in the right section... I did an experiment in class using a Geiger-Muller counter with the objective to find the amount of counts (how many photons hit the detector) due to natural radioactivity around my work station. I recorded 45 values of...

is will be correct if i will say that the graph number III has the larger mode between the 3 graphs ? if i wrong how can i know which graph has the larger mode? thanks.

Help! Binomial Distribution: Statistics for M.E's Homework Statement Four wheel bearings are to be replaced on a company vehicle. The mechanic has selected the four replacement parts from a large supply bin in which 10% of the bearings are defective and will fail within the first 100 miles...

Homework Statement First, let's derive the predictions for He-4 atoms at very low temps given the MB distr. Homework Equations The Attempt at a Solution Given the MB distr., if the ground state of the system is assumed to be at zero energy, then the ratio of occupation numbers...

HELP!Sums of Random Variables problem: Statistics Homework Statement 3. Assume that Y = 3 X1+5 X2+4 X3+6 X4 and X1, X2, X3 and X4 are random variables that represent the dice rolls of a 6 sided, 8 sided, 10 sided and 12 sided dice, respectively. a. If all four dice rolls yield a 3, what...

So, I have a very easy question. Imagine a roulette with 38 pockets (0,00,1,2,3,...36) Suppose you were to place bets on numbers 1,2,3,4. What is the probability that at least one of your numbers would be the winner in two consecutive spins of the roulette wheel. I am pretty sure the...

Homework Statement 1. The manufacturer of a low-calorie dairy drink wishes to compare the taste appeal of a new formula (formula B) with that of the standard formula (formula A). Each of 3 judges is given 3 glasses in random order, two containing formula A and the other containing formula B...

So, when people speak of "statistical physics", they're usually referring to "statistical mechanics". But statistical mechanics is really just a small subset of all of statistical physics (unfortunately, that makes googling for statistical physics difficult, because you'll mostly get stat mech...

Homework Statement 1. A bus arrives at a station every day at a random time between 1:00 PM and 1:30 PM. a) What is the probability that the person has to wait exactly 15 minutes for the bus? b) What is the probability that the person has to wait between 15 and 20 minutes for the bus...

Homework Statement Consider events A, B, and C such that P (A) = P (B) = P (C) = 0.2, A and C are mutually exclusive, B and C are mutually exclusive, and P (A ∪ B ∪ C) = 0.5. Give the value of P (A ∩ B), providing justification for your answer. Homework Equations The Attempt at a...

so, my dream job is work on the math end of artificial intelligence. i don't know how much of an option that is for me. i will be getting my undergrad degree in math with a stats minor here pretty soon, but I'm debating on getting a double major in stats and going on to grad school. does anyone...

Homework Statement Let k >= 3 be any integer. What is the probability that a random k-digit number will have at least one 0, one 1 and one 2? (as usual every number starts with either 1,2,...9 and NOT zero) Homework Equations b(x : n,p) = (n x)p^x*(1-p)^(n-x) where x = 0, 1, 2, ... ,n...

Homework Statement Let X and Y be two unknown variables with E(Y)=\mu and EY2 < \infty.Homework Equations a. Show that the constant c that minimizes E(Y-c)2 is c=\mu. b. Deduce that the random variable f(X) that minimizes E[(Y-f(X))2|X] is f(X)= E[Y|X]. c. Deduce that the random variable f(X)...

Hello, PFers! I'm a 3rd Year Mechanical Engineering Undergraduate, just started on a design project titled "Electrically-driven Tricycle for Disabled Children". My team of 3 are currently doing research to make a proposal with valid data before the deadline in the next 4 days. It's pretty...

At that website, you could look at a lot of statistics. For example: http://www.petersons.com/graduate-schools/cornell-university-graduate-school-field-of-astronomy-and-space-sciences-admissions-000_10028228_10088.aspx But the information at the website says this: I have a hard time...

Hi again everyone. I am revising my schedule for next semester because a schedule conflict came up, and am wondering, if i take statistical theory i (and ii later), would this be useful to me? I am a physics / electrical engineering major w/ math minor, i wish to go to grad school for physics...