Statistics Definition and 998 Threads

Homework Statement People in a given community who have a certain disease is 0.005. A test is available to diagnose the disease. If a person has the disease, the probability that the test will produce a positive signal is 0.98. If a person does not have the disease, the probability that the...

Homework Statement Find the probabilities that the value of a random variable will exceed 4 if it has a gamma distribution with (a) \alpha = 2 and \beta = 3 (b) \alpha = 3 and \beta = 4 [b]3. The Attempt at a Solution [/b} how would I even attempt this question?

Hi there, This is going to be difficult for me to explain, so I will try my best. My statistics is kind of rusty... I've been given census data to analyze and I'm having problems. The totals are all given by the government. For a specific attribute I've been given rows of different areas...

I was just wondering how exactly to appropriately modify the 1st and 2nd order stats when you want to weight a given sample more heavily. If \vec{X} is my vector of N samples and I have a weight vector \vec{W} of the same dimension, which ideally is measuring the reliability of each sample...

Homework Statement The proportion of people in a given community who have a certain disease is 0.005. A test is available to diagnose the disease. If a person has the disease, the probability that the test will produce a positive signal is 0.98. If a person does not have the disease, the...

Homework Statement A certain delivery service offers both express and standard delivery. Eighty-five percent of parcels are sent by standard delivery and 15% are sent by express. Of those sent standard, 80% arrive the next day, and of those sent express, 95% arrive the next day. A record of...

Homework Statement I am just trying to figure out how to calculate the expectation of something. The context is for a random sample from a normal distribution with known mean μ and unknown variance σ2. Homework Equations 3. The solution So for the purposes of this question we set θ = σ2 I...

How bad is my statistics knowledge based on the following mind map? Any concepts which aren't bold are the concepts that I know; the bold ones are the ones I'm currently learning. The mind map in question: http://i.imgur.com/4He3f.png What should I learn next based on my current...

I need some good online resources for learning statistics. Can I opt for video tutors, suggestions please...

Homework Statement Homework Equations The Attempt at a Solution Here's what I've tried so far, not really sure how to go on with these problems. Been reading the textbook up and down on Poisson processes! Any hints or help? Especially 1.B, 1.C and 2.B, 2.C

Let's say that a treatment A has been proven to have an impact on the levels of B with a given confidence interval. Let's also say that we know that the treatment C causes the treatment A to be imposed on our sample. Before the testing on the effects of C has been done, which statistical models...

Hey guys, I'm stuck on a question in my homework assignment and I was wondering if you could push me in the right direction? So here's the question: X and Y are continuous random variables with joint pdf f(x,y)= 4xy (0<x<1, 0<y<1, and otherwise 0). Find the pdf of T=X+Y using the CDF...

Applied math vs. statistics PhD -- job prospects I'm a math major considering pursuit of a PhD in applied math or stats when I graduate. I'm trying to ascertain the job prospects in these fields. Can anyone provide some information on how readily jobs are available in industry and academia in...

Does anyone here know any good Bayesian statistics, Bayesian hypothesis testing, Bayesian inference, etc. learning materials (preferably online)?

Homework Statement 1) S'pose we flip 2 fair coins, and roll one fair 6 sided die. What is the probability that the number of heads equals the number showing on the die? 2) We roll 4 fair six sided dice. What is the conditional prob. that the first die shows 2, conditional on the event that at...

Homework Statement For any cdf F(x) of a continuous random variable, show that \int_{-\infty}^{\infty}[F(x+b)-F(x+a)]dx=b-a for any a<b. Homework Equations The Attempt at a Solution Not really sure where to begin. I figure I can split the integrals and do u subs, and (after...

Homework Statement There is a city with 10 million people and an average human has 110 000 hairs. Prove that there is at least 2 people with the same amount of hair. The Attempt at a Solution I really have no idea of how to even start solving this problem. Sorry. Also, sorry for the...

Which branch of statistics and mathematics deals with extrapolations and trend analysis? That is, where one can estimate various trends (be they exponential, linear, etc.) that apply to our data and draw a trend which could extrapolate the future variation. Am I referring to the time series...

Homework Statement I am not sure whether the answer should be b or d. It says the average of the function and the vertical scale need to be determined. In other words I won't have to determine a_0 (the vertical shift) right? Because it did not mention that? Also what is the average...

It is said that is there already n bosons in a particular quantum state, the probability of another boson joining them is (n+1) times larger than it would have been otherwise. But if we apply this rule to calculate probability for one horizontally (H) polarized photon to join a bunch of n=99...

Hi Everyone, I am trying to rank football coaches and I'm a little confused on how to choose the weights to put in each variable. So far the variables I have decided to use are: total career wins, total winning percentage, current season winning percentage, current season total point...

Homework Statement Problem 2 Assume that the number Y of customers entering a store is a Poisson random variable with rate λ . Let X denote the number of these customers being a woman. The probability that a customer is a woman is denoted by p. Also, assume that all customers enter the...

I'm taking microfabrication right now and we will be making a flow cytometer on a chip. My question is--are the statistics that come from something microfabricated as good as the larger version? The idea is to use less reagents, materials, and sample, but if you use less sample can you...

Homework Statement The following data were obtained for trace elemental zinc in a particular sample of high purity (%Au> 99.99%). The results are given in mg Zn/ kg Au. 15.38, 15.17, 15.33, 14.88, 14.71, 15.42, 15.60, 15.22 Find the zinc content and the uncertainty at 95% confidence...

I've been taking this course for 2 weeks now. I have no clue what is expected to be known from a course like this. I will be speaking with my professor after the next lecture. Can anybody who has taken this course give me some tips to understanding what I'm supposed to be getting out of this...

Homework Statement Consider a string of N beads connected by N-1 rigid rods of length l. The system is considered as one-dimensional with rods only being aligned either up or down. The string is immersed in a fluid at temperature T and first bead is fixed at the origin y=0. A constant...

Did a search on statistical textbooks on the forum but did not find much except introductory statistical textbooks. Just curious as to what are some of the better intermediate to advanced level statistics textbooks on the market?

I'm a high-school/dual-enrolled CC student, and in the fall, I plan to take a Prob/Stat class that has multivariable calculus as a co-requisite (I'll probably do its sequel class in the spring as well). What exactly can you do in Physics or Chemistry with knowledge of Prob/Stat?

It has been a long time since I've done any statistics, so apologies in advance if I'm asking elementary questions. I wanted to do some nice statistics for a charity event that was held. The data I have is: Group A, 20 volunteers (total people in group 100 people.) Group B, 15 volunteers...

These questions are from a textbook. I attempted them, but couldn't get the answer. Please try which ever ones you can and provide a brief explanation if necessary of how to get the answer. 1. What are the odds against your rolling doubles in fewer than four rolls of dice? Attempt: First, I...

Hi, as we know a density operator \rho is defined to be a non-negative definite operator of trace class (with trace 1). We also know that for a given observable A, which is a (possibly unbounded) self-adjoint operator, the expectation value can be calculated as \operatorname{tr}(A \cdot...

I'm making the jump from math ed to pure math. I've done a bit more than the usual math-for-teachers stuff and my advisor is convinced I can pull it off, but if I sound nervous, this is why. I know what to review and study up on before fall semester for two of my classes but I'm at a loss...

Hello, Just had a question regarding statistical analysis. I'm trying to calculate the average of 4 numbers from a data set of 6 numbers in excel without manually choosing to average only the 4 numbers. e.g. 85 20 32 45 27 3 (total mean = 35.3 desired mean = 31) 100 30 27 40 21 1...

Like a previous thread also this is opened with the purpose to answer to statistic questions proposed in other sites that didn't receive answer for not less than three days. Let’s start with an interesting problem about ‘Random walking’… Posted on 11 26 2011 on www.artofproblemsolving.com by...

I just graduated with a B.S. Math and Physics Minor. I took Probability but not Statistics. I also didn't get a chance to take PDE. I'm looking for some good textbooks on the subjects.

A text says that if you calculate the linear regression of data points and you get the equation y=mx+b with an r2 value, the error in the slope is given by: δm/m=2(1-r) No explanation was given. Could someone please explain this formula? Thanks!

Homework Statement Let's say the independent variable (in statistical terms) A depends on variables B, C and D. We perform tests, and find out that the variable A causes "something" with the values of B, C and D equal to B2, C2 and D2. Let's also say that A with variables B, C and D of B1...

Hey everyone! Exam practice, that time of year. In this problem 13 with correct answer C, I'm not sure how they get the test statistic: http://i.imgur.com/doar3.jpgI think they want you to use a F-test, that tests the entire model, which is calculated by: F= ((R^2)/ K)/ ((1 - R^2)/(n-K-1))...

When you consider a electron L×L×L box, I think I understand how to derive the DOS-spectrum. Unfortunately, when a small change is made to the problem, I really don't understand what to do, so I probably don't understand the theory at all.. This is the question: Homework Statement Consider a...

I need a software for statistics, so it should make plots, fitting curves on points, calculate the uncertainty of measurement etc. Which software do you recommend?

My professor gave me data points representing living cells on a rectangular plane and was told to analyze their spatial pattern, i.e., do the date points on the finite plane have a tendency to be clustered, random, or dispersed. I successfully accomplished this for points on a continuous plane...

What are the differences between these three undergraduate degrees? I am contemplating on being an Applied Mathematician. I have a natural desire to solve statistics and probability questions. If I were to come across a real life problem I would try to involve these concepts in solving them...

Hi, I have K i.i.d. exponentially distributed random variables with mean unity. I need to find the CDF and PDF of the summation of the largest two random variables. How can I do that? The problem in this case is that the combinations are not independent. Thanks in advance

Hello, I apologize in advance if I have missed the right place to ask. I'd be grateful if you could forward me to the right place, if that is the case. Google didn't help, so maybe someone here can point me in the right direction: 1) "If the input to a LTI system is a Gaussian random...

Hi there, I enjoy mathematics, programming, and chemistry. However, I don't enjoy physics at all and I'm not good at it (if it's okay to say that on PhysicsForums haha). I think that makes engineering an unlikely path for me. Degrees in math or computer science at my university require...

Hi everyone, I'm doing a research subject about the correlation between the lunar tides and earthquakes, but I've never study the statistics. Could some one suggest me a online course or something like that to give me some ideas of how to study the correlation between events? Thank you in...

Hi all, I've been asked to learn how to use the R for statistics software at work. I know "basic" stats theory such as linear/multiple regression, t-tests, ANOVA etc, and have used other software packages such as Excel, SPSS, but never R. Can anyone recommend any good books/websites to get me...

I'm going to try for a triple major in physics, math, and computer science. I already have a CS related associates, so many of those courses as well as electives are knocked out already. The plan is to master in astrophysics/cosmology, and the end goal is to work for NASA. I read in another...

Homework Statement In class we have to determine whether something is nominal, ordinal, interval or ratio and with the last 2 (ratio/interval) you have to state if they are discrete or continuous. Homework Equations n/a The Attempt at a Solution Height of Mt Everst above Sea level=...

After having read the first half of Introduction to Statistics and Data Analysis by Peck and Olsen, I must say that the book is complete garbage. Does anyone know any good books on intro statistics that provides proofs for its theorems and the axioms of probability? It should be focused more...