# mathematical statistics

1. ### A basic question about chi-square test

There is a test to examine the usage of different English words by male and female students. So there are two columns of data (male and female students), 30 rows(each row is the frequency of different English words used by male and female students). I find an online chi-square calculator, which...
2. ### Help Determing What Distribution

I believe I have answered a), as L~Gamma(N,1/20), therefore mgf = (20/(20-t))^N (if wrong please feel free to correct me). It has been defined that L=-ln(U), and I am finding difficulty in determing what distribution U would be classified as. Once classfieid, I believe that finding the mean...
3. ### Evaluate performance

i have 5 variables of game's data which is evaluated on some logic . example : level = 100% objective = 100% retry = 100% successful moves = 80% score = 25000 now i have such data of every user, above one is just example , now i want to measure performance of such user and using this 5...
4. ### Book recommendation for Mathematical Stats

So I've read Tanis and Hogg, and Ross's Mathematical Statistics books and understood them fairly well. Still when I try to read some other Stats books I always encounter something I've never seen before that keeps me from making progress. To give some examples, in Gelman's Bayesian Data...
5. ### mathematical model to build a ranking/ scoring system

I want to rank a set of sellers. Each seller is defined by parameters var1,var2,var3,var4...var20. I want to score each of the sellers. Currently I am calculating score by assigning weights on these parameters(Say 10% to var1, 20 % to var2 and so on), and these weights are determined based on...
6. ### Calculating a one-way anova with just means, stdev, and sample sizes

Hi How can you determine the sum of squares total, sum of squares within and between, only knowing the mean, standard deviation and sample size of two groups e.g., group 1: mean 5.67 SD 3.055 sample size 3 group 2: mean 14.33 SD 2.081 sample size 3 Many thanks for any help and...
7. ### Making sense of the parameter delta in this equation.

Hello, I was reading this paper about pollen dispersal directionality and I am trying to make sense of the so-called directionality parameter \delta The Statistical Model On pages 4 and 5 they explain their analysis under the section statistical procedure. More specifically, in the first...
8. ### Maximum Likelihood Estimator - What did I do wrong?

For a X_1,…,X_n random sample from a uniform distribution from [0, 2*theta+1], I was asked to find the MLE. The pdf: f(x|theta) = 1/(2*theta+1) for x in [0, 2*theta+1] and 0 otherwise. I determined the likelihood(theta)=L(theta)=(2*theta+1)^-n Then the log-likelihood to be -n*(2*theta+1)...
9. ### standard deviation for an equation

Hi, I am trying to figure out how to get the standard deviation for two equations. The first one is quite simple; it's just how to find the SD for a part of an average value. I have the SD for an average amount of element in 4 values e.g. average = 118 mg/kg and SD = 48 mg/kg I am...
10. ### I Need Help with Poisson Distribution Problem!!

I don't know where to even start with this Poisson Dist. problem, can anyone help me solve this??? The Hillel Sandwich Shop specializes in delivery of sandwiches in New York's financial district. Customers phone or fax Hillel their orders, which are then delivered directly to the customer's...
11. ### Proof the sum of two CDF's is a CDF.

This is a question my instructor asked in the last midterm exam but nobody was able to solve and he's suggesting it may come out again in the finals: If F(x) and G(X) are two CDF's, prove that H(X) is also a CDF if H(X) = F(X)+G(X)-F(x)G(X) He said something about right...
12. ### Sum of independent beta-Bernoulli random variables

I'm looking for the distribution of the sum of independent beta-Bernoulli random variables, that is Bernoulli random variables with beta-distributed parameters, x_i ~ Bern(p_i) with p_i ~ beta(alpha,beta) (same alpha and beta, of course). I guess one can work with convolutions or characteristic...