Statistics Definition and 998 Threads

I am a physics major and unfortunately this semester there is almost no classes that I can take in my major field of study due to not having the proper prerequisites. So I am looking for a course that will keep my math skills honed. I am really interested in taking statistical methods which...

I will be applying to a master's program for math hoping for acceptance in the Fall 2011. My only math background is Statistics, economic statistics, Calc I, Calc II, Calc III (multivariable), and Linear Algebra, but this Spring I will be taking a class titled "Bridge to Advanced Mathematics"...

Homework Statement let X be a random variable with uniform p.d.f over the interval (0, theta) Determine whether 2X-bar (sample mean) is an unbiased and consistent estimator for theta Homework Equations bx(theta)=EX-theta The Attempt at a Solution By using normal...

Homework Statement A source is supposed to emit photons with spin +/-1 independently at equal rate. a) after measuring 4 photons, all have spin +1; b) after measuring 100 photons, 60 have spin +1. at which confidence level can the hypothesis be rejected. Calculate for each of the...

Statistics Need Help !1 I am doing review for a test and i still can not get this problem..HELP Please The scores on a test had a mean of 2.725 and a standard deviation of 1.329. A teacher had 61 students take the test. Although the students were not random sample, the teacher considered...

Well am not looking for someone to solve the problems ,,, am looking for somone telling me how to use excel to solve some problems. with excel functions. the problems " 1.From this population of 500 households, select a simple random sample of 50 households (Use the program...

how can i use excel to solve some Statistics problems ,,, hi all ,,, am looking here for help. to know how to solve some stat problem with excel could someone help me please ,,,, :rolleyes: well the things I want to know are. " A data set was gathered from 500 households (you...

IS graduate school really worth it in this economy or is the safe way out?

Homework Statement This is just a general question about understanding. What is the difference between a joint distribution functions vs. a joint density function. Homework Equations The Attempt at a Solution Are joint density functions basically the joint distributions of...

1)X=0,1,2,3,4 FIND E(X) The attempt at a solution: E(X)= (4 X)(.4)X (,6)4-X 2) YOU CAN TOSS A FAIR COIN UP TO 7 TIMES.YOU WILL WIN 1000$ IF THERE TAILS APPEAR BEFORE A HEAD IS ENCOUNTERED. WHAT ARE YOU CHANCES OF WINING ? The attempt at a solution: 2*2*2*2*2*2*2=128...

Originally, it is derived from the weight of a confuguration,i.e. how electrons are distributied in different energy level:n=gexp(a+be) It gives the number of electrons in each energy level.However suddenly it can be apply to a cloud of gas?? By dividing a box of gas into different energy and...

Homework Statement The random variable X has uniform density on the interval [0,2], so that p(x)=1/2 for x in the interval [0,2] and p(x)=0 otherwise. Give the range of a (between minus/plus infinity) such that E[X^a] < infinity. Homework Equations The Attempt at a Solution I...

Homework Statement Simple regression without a constant Yi = Bxi + epsi for i = 1,2,...n epsi are independent and N(0, sigma^2) distributed, B and sigma^2 are unknown. All my sums are from i = 1 to n The question is: Explain why: \frac{\hat{B} - B}{S} \sqrt{\sum{x_i^2}} is...

Statistics Help--Joint pmf and marginal pmfs Homework Statement Let X1 and X2 be iid discrete uniform random variables with support on the integers {1,2,3,...,n}. Find the joint pmf of Y=max(X1,X2) and W=min(X1, X2). Find the marginal pmf's of W and Y Homework Equations The...

1. The problem statement: A set of measurements of a parameter x has a normal distribution with mean of 50 and standard deviation of 1. If there are a very large number of measurements, approximately what percentage of measurements would you expect to be in the range 48 < x < 50...

Hello, I got a question regarding the probability amplitudes of polarization. Say you rotate the polarization amplitudes to 45% so the photons that pass through a filter have 50% probabilty of vertical or horizontal polarization. Is that 50% probabilty much like the probabilty of say...

Homework Statement In his paper "regression towards mediocrity in hereditary stature" Francis Galton collects data on stature of children (928 obs.) & parents (205 obs.) now as part of my project i have been asked to recreate the original data set. However taking children the data set runs...

Hello everyone. I am a 12th grade Portuguese student and have a theoretical question to pose, which is probably more related to maths & statistics. In our class, we made an experiment with an Atwood Machine and deduced the formula for the acceleration of the system (ignoring the string's...

Homework Statement Find the Z value that corresponds to the given area. http://img163.imageshack.us/img163/3785/problem1v.jpg The Attempt at a Solution What I did was go to Table E and find the closest number to 0.0166 which was 0.0160, and the Z numbers were 0.04 and 0.0. I then added them up...

here is the notes: we have the MB statistics or distribution ns = Agsexp(-es/kT) (1) This is only for a set of discrete energy levels es. In this section, we shall see how (1) can be applied to a variety of situations. For instance, how can we use this distribution for an ideal gas which...

Homework Statement Let X1, X2, ... Xn be n mutually independent random variables each of which is uniformly distributed on the integers from 1 to k. Let Y denote the minimum of the Xi's. Find the distribution of Y. Homework Equations The Attempt at a Solution I can see that P(Xi = j) = 1/K...

What are the odds that no one in my group has an October birthday? There are 43 people in the group.

Homework Statement I am working on some statistics problems found in a introductory book on statistics, however i am having trouble with the following problem. It reads, You are quoted some statistic, such as the number of imports into a country, a companys profits, or the number of seconds...

Hey everyone, This is for someone who has used R. Please tell me how can we sum a function with a free parameter in R. I used the normal command f=function(n) sum(body of function containing n) it does not show any warnings till here, but when I plot this sum vs n (which i now define as a...

Can someone please help me figure out if my attempts are right? or if I am using the right method? in one study on 20 men. the upper confidence limit of a 90% confidence interval is 62.3 grams, and the upper confidence limit of an 80% confidence interval is 54.8 grams. What would the lower...

Hi guys, I'm having a hard time figuring out these two expectation problems below. Can someone please help me? For this problem, here's what I got: x...300...? p(x)...0.998...0.002 I can't seem to figure out what to put in the ? (loss). Maybe i just don't understand the wording of the...

Hi guys In my statistics book there is an example. They say that we see 3 occurrences of type A, and theoretically expect 7. This is a difference of 4, since we know that the standard deviation is 1.65 (they calculate it), then the difference is 2.4 standard deviations. Looking at a table of...

Hi, Well, I thought posting this question here is more relevant. I want to self-study a book about error analysis and data fitting. I have two books available, the one by bevington and robinson: "Data Reduction and Error Analysis for the Physical Sciences" and the one by taylor: "An...

R statistics program, is there a "and" statement I am trying to use R and need to use "and" as in if x is larger than y and smaller than z. I have tried to google and the manual, but I can't find it.

hey so i am trying to solve the following question but i have no idea how to solve it. I am confused by the %'sConsider a similar study done that shows that 96 % of those born in Canada can swim but only 83 % of new Canadians can swim. In a random group of 11 new Canadians, find the probability...

Homework Statement An analyst is presented with lists of four stocks and six bonds. He is asked to predict, in order, the two stocks that will yield the highest return over the next year and the two bonds that will have the highest return over the next year. Suppose that these predictions...

Homework Statement Suppose P(A) = .6, P(\overline{A} | B) = .4. Check whether events A and B are independent. Homework Equations Two events A and B are said to be independent if P(A|B) = P(A). This is equivalent to stating that P(A \cap B) = P(A)P(B) If A and B are any two events, then...

Hey, I am an undergrad planning on grad school for statistics next fall. I have the summer and next semester to take some courses. I would like to take some math that interests me but I also would like to do something that will be useful to graduate school. I have pretty much taken minimal...

Homework Statement A jet engine manufacturer estimates that the chance of a “critical-item” failure within a jet engine’s afterburner module is approximately 1 in 220. What is the standard deviation of the number of launches, before a “critical-item” failure occurs within a jet engine’s...

I am using this book for a mathematical statistics class I am in. I have an account with cramster to check answers since they have solutions to nearly the entire text, but they are HORRIBLE. Half of the time they are dead wrong and they always lack decent explanation which is pretty key in...

What is the difference between applied and mathematical statistics ? Does applied statistics skip a great deal of necessary knowledge ? Is applied statistics enough to construct statistical models?

I'm learning modern physics and my book starts out with teaching distribution functions, but not to well. I need an intro that is not afraid to use an integral, but yet does not breeze through it as fast as this physics book. The book wants to know distribution functions to learn about plank's...

Homework Statement Have the notebook in here but can't connect what's really happening AND very easy stuff ? for example : 1) if A={a,b,c} A U B={a,b,c,d,e} A\B={a,b} B=? 2) n(A)=12 n(B)=10 n(A U B)=18 n(A\B)=? 3)This one is tricky n(A)=4*n(B) n(A\B)=20 A...

A certain number of persons (for example 100) choose the days of the week they prefer for a meeting, a fest, an event. The day preferred by most of the persons (for example 40) is Monday. If the meeting is every Monday, at the end of the year the number of persons who partecipated would be the...

Homework Statement Hi Say I have the following bin sizes, where the number in paranthesis is the amount of data points contained in the bin: 20-29 : (2) 30-39 : (7) 40-49 : (12) 50-59 : (14) How would I go about and find the mean for this binned data? I know that I should use...

Homework Statement The average salary for an employee at ABC Ltd is £30,000 per year, with a variance of £4,000,000. This year, the management plans to award every employee a fixed end-of-year bonus of £500 and an incentive bonus that is equal to 10% of the employee's salary. a) What is...

Homework Statement Mean of 25 and standard deviation of 5. Rescale the test using linear transformation so that the mean is 100? and the standard deviation is 20... Homework Equations xnew=a+bx The Attempt at a Solution I don't know...15+4x? I really don't understand how to...

What sort of a blend would this be? Let's say I am interested in being part of a research in some physics discipline but not necessarily as a physicist but as a statistician/data analyst. Like The guys/girls who compile, analyze etc the data from experiments on particle interaction, for example...

Hi, everyone: I am teaching an intro. stats course, and I want to find a convincing explanation of how we can "reasonably" estimate a population parameter by taking random samples. Given that the course is introductory, I cannot do a proof of the CLT. Specifically, what has seemed...

There are lots of books on statistics and probability that contain examples such as throwing a die or the number of buses passing through a particular junction. However these are not examples that students find interesting or tangible in any way. Are there any resources that introduces...

If Var(Y)=\sigma^2, then Var ( Y2 ) = ?

Homework Statement the weight of items produced by a production line is normally distributedwith a mean of 12 ounces and a standard deviation of 2 ounces. a. what is the probability that a randomly selected item will weight between 8 and 16 ounces? (DONE) b. what is the probability that a...

Homework Statement the weight of items produced by a production line is normally distributed with a mean of 12 ounces and a standard deviation of 2 ounces. Suppose that quality control requires the weight of items to be within 8 and 16 ounces. You select 7 items at random (each item is...

need help with this problem x~normal(mean= 12, stdev=2) item weight from 8 to 16 ounces i have a random sample of 7 items and need to find the probability that 3 of those items fulfill the weight each item is independent this is what i got at the moment z=(16-12)/(2) = 2 p(z<2)-p(z<-2)...

Hi all, I'm wondering how to gauge the chances i have of making it into a PhD program. First approximation: took ratio of accepted students to number of students who applied. But: that produced a 116/487 = 24% chance of being admitted to U-Cal San Diego, verses a 45/260 = 18% chance of...