1. D

    Why do we differentiate between log linear vs. exponential time series

    Given by definition for a function to be linear on a log plot, it must be exponential (bc log_a(e^x)=x), why do we differentiate between log linear and exponential things?
  2. N

    MGF; exponential

    In a) I've problem understanding if I should compute the mgf of the function f(x) or mgf of expected value?
  3. S

    Logistic Regression: Estimate

    TestTrans YTrans N TotalRRRR055104.7%50.0%131691005.7%31.0%Total3674
  4. E

    Resulting expected value of a bounded exponential pdf

    I need to determine the distribution function of an exponential random variable with mean 2, given that its outcome is larger than 2 and give the resulting expected value? I know that the mean is 1/lambda, so lambda should be 1/2. I get that way 0.5*e^(-0.5x) >= 2. How can I deal with the...
  5. M

    Why regression models use log or exponential value?

    I am not very familiar with statistic. Any statistician can help me to clarify what the difference are between exponential value and log value. I found in academic papers that regression models are usually shown in exponential value or log value. 1) what is the difference between them? 2)...
  6. I

    Problem log(0) practical solution?

    Hello everyone, I want to model the association of a score (range 0-125) and age with an exponential approach because my scatterplot show an exponential progression. My approach is: I do log(score) -> do a linear regression with age as covariate -> do exp(regression coefficients)...
  7. J

    Exponential Regression to Forecast Future Growth

    Hi, I'm a C# programmer and am not a math major. I have a programming problem that I am trying to solve and hope that someone here can help me solve it. I need to use Exponential Regression to forecast the future earnings of a company. I have the past 10 years of quarterly data. I can do...
  8. F

    exponential EWMA- statistical process control to monitor time between events

    I am looking into control charts to monitor time between events for rare events. A quick literature review revealed that the following four methods are worth investigating: Cumulative Count of Conforming (CCC) chart; Cumulative Quantity Control (CQC) chart; the exponential CUSUM and...
  9. S

    Expectation-Maximization-Algorithm: example exponential family

    Hi everyone! I’m in desperate need of an example (one with actual numbers!) for the EM-algorithm concerning exponential families. I spend a lot of time trying to find one, but unfortunately didn’t succeed. The only one I found, is a very easy one, that I unfortunately don’t fully understand...
  10. P

    Xn~Exponential(.5) -> Xn~Normal. Use Chebychev's inequality

    Xn are iid Exponential(.5). After using the central limit theorem, Xn is Normally distributed. Use chebychev's inequality to find out how large n be so that P(|Xn-2| < .01) > .95. I tried working on it and got the E(Xn) = 2n and Var(Xn) = 4n, and P(|Xn-2n| > .01) < (4n/(.01)^2)(1/n)= 40000...
  11. S

    Help please with the problem

    W is a standard exponential distribution. Q is distributed uniformly on [0,2pi] W and Q are independent. R=sqrt(2W) -pi/2<=a<=pi/2 - constant. U=Rcos(Q) V=Rsin(Q+a) Need to prove (U,V) has bivariate normal distribution with correlation equal to sin(a) Its hard for me to solve it, I...
  12. A

    Functions of Random Variable.

    Let X be exponential(lambda), and let Y=max(1,X). Find the cdf of Y. Also sketch the cdf. Suppose that X is discrete with pmf p(0)=p(1)=2p(2) (and zero otherwise). Find the pmf and cdf of X. How would you simulate the random variable X starting with U, a uniform[0,1] random variable? That is...