1. M

    Sum of two normal distributions

    Hello, I'm doing data analysis research and currently I'm trying to fit the simple model to a data sample. From physical speculations I know that the distribution should be a sum of two normal distributions with different parameters (mean, width, area). I fitted my data with the model and it...
  2. B

    Moments of a random variable involving numerous Binomial Distributions

    Mean, Variance, Skew, and Kurtosis of X I am editing my post because it might have been unclear. Suppose X is a random variable involving 4 binomially distributed random variables: X = y1(p, 1/2 (a + b)) - y2((1 - p), 1/2 (a + b)) + y3((1 - p),1/2 (a - b)) - y4(p, 1/2 (a - b)) I wish...
  3. M

    Raw moments of 3-parameter Weibull distribution

    Hi, I know that the formula for computing the raw moments of 2-parameter Weibull distribution is: Mu'n=b^n*Gamma(1+n/c), where b and c are scale and shape parameters, respectively. However, I couldn't find any exact formula for a 3-parameter Weibull distribution. Is there any simple formula...
  4. K

    Getting pdf of X given the moments

    Please help me with the following question. m2 = E(X^2) = 1 m4 = E(X^4) = 3 m6 = E(X^6) = 9 Find all possible distributions of X.
  5. S

    Is it possible to plot pdf from moments ??

    Hi guys, I'm a mechanical engineering student and new to statistics. I'm facing a little bit of a problem with pdfs. I have used the Quadrature Method of Moments to find 6 moments of an unknown particle size distribution function. I'd like to know if there is a way to plot the distribution...
  6. B


    Hello any and all, I am no statistician so does the term "4th-variance" mean anything to someone? I am attempting to replicate the technique found in the publication below. The paper suggests that the 4th-variance is related to the expectation operator. The paper also discusses moment...
  7. F

    Can you give me some references?

    I need the derivation of the parameters of distributions including: Gumbel, Weibal, Lognormal and Gamma with both method of moments and maximum likelihood methods. Can you introduce me some references for the full derivation? If you are referencing book I appreciate if you can do more than one...
  8. D

    Method of Moments Help

    I was doing a problem. I forgot to mention in the following images, but the question is to find estimates for the two parameters using method of moments. The sample size is 4 with Y1=8.3, Y2=4.9, Y3=2.6, Y4=6.5