Statistics Definition and 998 Threads

I don't know much algebra (I kind of skipped it and went to geometry), but I do sort of understand statistics. I can certainly perform a z-test or a t-test and know when they should or shouldn't be used.

Homework Statement I am doing a practice final exam in preparation of my actual final exam next week. Here is the link. I am doing problem number 2. http://www.math.stevens.edu/~ifloresc/Teaching/2011-2012/MA222S12/Final_Exam_Summer2011.pdf The Attempt at a Solution So this seems...

This thread is opened by me with the purpose to answer to statistic questions proposed in other sites that didn't receive answer for not less that three days. Let's start from that question posted on mathhelpforum.com by Frida on 04 22 2012... A variable of two populations has a mean of 7.9...

Homework Statement Let Xi ~ iid f(x) = (2x)I[0,1](x), i = 1,...,n. Find the distribution of X(1). What is the probability that the smallest one exceeds .2?

Homework Statement http://studyterps.com/files/STAT401-FE-SP09-CREMINS.pdf #5Homework Equations The Attempt at a Solution How did they get the MSTr and MSE form that table? I'm aware of the formulas such as MSE= SSE/(N-k) and so on, but usually you have some values given. Do I first...

Homework Statement Let X1,…,Xn denote a random sample from a population with mean μ and variance σ^2. Assume that both μ and σ^2 are finite but unknown. Let X denote the sample mean and S^2 denote the sample variance. Are the following statements true or false? A-There is no difference...

So i have a list of different person height (n=100) between 5 and 8 foot. 1) Test H0: mu = 5.9 vs Ha: mu (not) = 5.9ft with alpha = 0.05? 2) Test H0: Student height has a normal distribution vs H1: Student doesn't have a normal distribution alpha = 0.05 using X^2 distribution What does it...

Hello there, Is real analysis really important in the process of learning statistics? The reason is, I suck at real analysis(actually, I failed it) and do really good at stats(I am in my third yr. at uni.). Should I continue studying stats or switch to another major? I am looking...

Homework Statement In math 334 one semester, the average student made 1200 computations per month with a standard deviation of 150 computations. Assume that the number of computations is approximated by a normal curve. Find the percent of students making between 1200 and 1600 computations a...

I have the following data set: condition A and condition B, with 4 replicates recorded over 3 time periods. Hypothetically you can think of it as measuring the height of the sun in the sky in winter (A) compared to the summer (B), in 4 nearby villages (independent observations) over 3 days...

I never really thought that I had a poor gpa until an interviewer said they won't even look at someone with less than a 3.5 gpa. I thought that was a little extreme and it has me wondering where I stack up. Does anyone know of a place that I could find some statistics on the matter?

Hi, I know the title of this thread is very vague, so I apologize. How much calculus is actually used in statistics? I've heard Linear Algebra is one of the most used fields of math in statistics, but am interested in other opinions.

Homework Statement A taxicab moves between the airport, Hotel A, and Hotel B according to a Markov chain with transition probabilities: P(airport → A) = 0.7, P(airport → B) = 0.3, P(A → airport) = 0.9, P(A → B) = 0.1, P(B → airport) = 0.8, P(B → A) = 0.2. A-If the taxicab starts...

Hi all! I've got a question concerning Wick's theorem. I followed the proof in the book by Fetter and Walecka and it works well for particles with "normal" statistic, that means for bosons and fermons (commuting or anticommuting). But what about anyons, particles which don't commute just with a...

I am trying to find a correlation between colony collapse disorder and the change in Earth's magnetic field. I don't understand the whole physics of measuring Earth's magnetic field but I am guessing that there is some sort of measurement that has been recorded every year? I have been...

Should i choose pure mathematics or statistics as a major for my degree? I intend to do my masters n PhD to become a lecturer. which is d better path if i want to be an academician? i also heard dat pure maths esp math proof is vry rigorous but I'm nt sure if i'll like stats.. any advice?

Homework Statement Consider N(μ, σ2=40) distribution. To test H0:=32 against H1:μ>32, we reject H0if the sample mean \overline{X}≥c. Find the sample size n and the constant c such that OC(μ=32)=0.90 AND OC(μ=35)=0.15. Homework Equations What I don't know The Attempt at a Solution...

Ok so I started this debate with my teacher. It is about this formula for finding the Quartiles of grouped data. Let's take a look at this data: With ungrouped data, 1 2 3 4 5 6 7 8 9 11 12, for example, we solve for Q1 as (at least that's what she taught us): Q1 = 1(12) / 4 Q1 = 3...

This question concerns estimating the PDF of noise, based upon observations of a data stream consisting of noise embedded with transient signals. I would like to know if my Proposed Solution is a correct approach. Suppose I have "long" stream of seismic data, consisting of noise, and with...

Homework Statement My mean is 5.80 My standard deviation is 0.64 The largest number does not exceed 7 1) What is the probablity the probability of randomly selecting a number, and the number being over 2 σ from the mean. 2) For a sample of 30, what is the probablity the mean will be over 2...

Homework Statement My task is to explain why the sample statistics I have obtained differ from the population statistics I have obtained from some data - using "concepts taught in class, if they exist". I have calculated x̄ and s, as well as σ and µ. Homework Equations First of all, the...

Can someone please explain how the standard deviation is relevant when we are talking Brownian motion? And why is statistics important when we want to understand the movement of a brownian particle?

Homework Statement Assume z_1, ..., z_m are iid, z_i = μ+\epsilon_i \epsilon_i] is N(0,σ^2) Show that f(z; μ) = g( \bar{z}; μ)h(z) where h(·) is a function not depending on μ. Homework EquationsThe Attempt at a Solution Now z is normal distributed with mean my and variance sigma^2...

Hi. I'm reading an introductory section on the Bose-Einstein condensation of a non-interacting, spinless boson gas. I'm confused by the claim that the ground state is in a coherent state with eigenvalue sqrt(N0) exp(i theta), where N0 is the expected number of particles in the ground state. The...

Homework Statement I'm trying to study off an old practice midterm for my upcoming statistics midterm. The midterm is attached. Part One is the following problem: The effect of a new antidepressant drug on reducing the severity of depression was studied in manic-depressive patients at...

Homework Statement Let X1, X2, ..., X9 be a random sample from a normal distribution, Xi~N(6,25), and denote by Xbar and S^2 the sample mean and sample variance. Use the standard statistical table for normal distribution. Homework Equations E[S^2] = δ^2 = 25 S^2 = (ƩXi^2 -...

Homework Statement (From Probability and Statistical Inference, Hogg and Tanis, Eighth Edition, 5.1-5) The p.d.f. of X is f(x) = \theta x^{\theta - 1} for 0<x<1 and 0<\theta<\infty. Let Y = -2\theta \ln X. How is Y distributed? Homework Equations Um... Fundamental Theorem of...

Hello. Am I counting right with these problems? I can't remember exactly how they were worded, but I remember what they were asking... 1) Given 20 men and 20 women, how many groups of 12 can you make with 6 men and 6 women. I said 20.Combination.6 * 20.Combination.6. 2) given S= {1, 2...

I´m wondering how to find out something about distribution functions after I´ve calculated the scewness. I have 15 numbers, mean is 3.206, highest is 7.028 and lowest is 0.9209. Variance is 2.958195. I calculate the skewness and got 0.945. I´m wondering which of the following distributions is...

Homework Statement Suppose that the weights of airline passenger bags are normally distributed with a mean of 48.14 pounds and a standard deviation of 3.71 pounds. Let X represent the weight of a randomly selected bag. For what value of c is P(E(X) - c < X < E(X) + c)=0.95? Give your answer...

I'm about to finish my lower division math requirements, which will cover everything for all my lower division coursework for all three subjects, bar 3 programing coures, one that can be taken next quarter, and the other 2 which can be taken concurrently in the beginning of next quarter. If I do...

Given the fact that X and Y are independent Cauchy random variables, I want to show that Z = X+Y is also a Cauchy random variable. I am given that X and Y are independent and identically distributed (both Cauchy), with density function f(x) = 1/(∏(1+x2)) . I also use the fact the...

A1 Computer has 15 tablets stocked, but four of them were actually defectives. A client bought two tablets from A1 Computer. If both of them are good, things are fine. If the client gets one defective machine, A1 Computer will replace it and give a $100 rebate to the client. If the clients...

In 2007, 52% of all immigrants to Canada were females, 25% were under 18 years old, and 12% were females under 18 years old. a. Find the probability that a randomly selected person who immigrated to Canada in 2007 was a female and over 18 years old. b. Find the probability that a randomly...

Statistics: Question about "mild" and "extreme" outliers. I am studying statistics, and have noticed the definitions of the mild and extreme outliers. Mild outlier: Between 1.5q and 3q away from the nearest quartile, where q denotes the interquartile range. Extreme outlier: More than 3q...

Homework Statement I've attached both the problems into one image to make life easier since problem 1 has a diagram and the other does not. Homework Equations Bayes Theorem : P(A|B)P(B) / [P(A|B)P(B) + P(A|B')P(B')] B' = B Complement The Attempt at a Solution well for the first one i don't...

Homework Statement 1) A computer firm presently has bids out on three projects. Let Ai = {awarded project i} for i = 1,2,3. Suppose that P(A1) = 0.20, P(A2) = 0.25, P(A3) = 0.28, P(A1∩A2) = 0.10, P(A1∩A3) = 0.06, P(A2∩A3) = 0.08, and P(A1∩A2∩A3) = 0.01. Compute the following...

Homework Statement A random variable X has three, and only three, possible values, 0; 2; 4 with the following probability distribution: Probability: Getting a 0 is 0:7 Getting a 2 is 0:1 Getting a 4 is 0:2 Let X1 and X2 be two independent random variables with this distribution. (a)...

BLS has released data on unemployment for the month of January. http://www.bls.gov/news.release/pdf/empsit.pdf What I want to ask about is a blog from Karl Denninger on market-ticker. http://market-ticker.org/akcs-www?singlepost=2858099 He states that he used the "correct adjustment"...

I've calculated the mean difference of my (normally distributed) data set. The mean difference is defined as: Now, I'm trying to calculate the "mean difference deviation" in order to generate a confidence interval for this quantity ( "95% of the differences in the set are greater than...

hey guys, some hopefully easy stat questions if you will Im wondering about translating one statistical distribution to another, like going from: Bin(n,p) to N(np,sqrt(npq)) where q=1-p or that Po(au) is roughly equal to N(xu,sqrt(xu)) Im mostly sitting scratching my head on which...

Does anyone have sources on how many PhDs of each field is being produced each year? i.e. how many physics PhDs graduate each other, how many in mathematics, etc.

What are the "natural" generalizations (if any) to Bose and Fermi statistics? fermions: 1 particle per state Bosons: unlimited number of particles per state do people consider things in between like states with a capacity n? are there other generalizations of these statistics? Thanks!

Hi everyone! Lately I have been trying to improve my typing speed, and have been playing a game called Type Race, where you type various short passages (the passages are selected at random from a text bank) and your score in WPM is recorded. What I want to do is determine whether or not my...

Suppose that IQ scores have a bell shaped distribution with a mean of 104 and a standard deviation of 14. Using the empirical rule what percentage of IQ scores are less than 76? Please do not round your answer. So far this is what i have 76 -104= -28 -28 __ = -2 14 *How do I...

Hello, I've just began my first probability class, and let me tell you, it's a doozy. It reminds me a lot of my physics classes: There's a general sort of way to go about solving a problem, but each problem is completely different from the other. If this was the entire major, I'd stop here...

(This question was previously posted to sci.math.research. I only received one reply; sadly the advice therein conflicted with section 9.1 of H.A. David's "Order Statistics" - and probably with the fact that there was such a field of study as "r-extreme order statistics" - hence my reposting it...

Homework Statement http://img687.imageshack.us/img687/7963/screenshot20120102at185.png Homework Equations The Attempt at a Solution I understand how to compute a Chi-squared test, but I'm a bit confused about the wording of parts a) and c). Could someone possibly simplify it for...

Would you say that these "salary by degree" statistics are accurate? http://www.payscale.com/best-colleges/degrees.asp I know it's rude to ask people how much they make, but if you guys don't mind, could you at least tell me if these numbers are realistic, compared to what you've seen? This...

Hallo, I posted this in General Math, and I decided to post it here also because this room seems more appropriate. The formulas and part of the text are quoted from "Klimontovich - Statistical theory of non-equilibrium processes in a plasma": Let N_{a}(\textbf{x},t)...