Let X = {X1, X2, . . . , Xn} be a random sample of size n from the geometricdistribution with probability mass function:pX (x; π) ={(1 − π)x−1π for x = 1, 2, . . .0 otherwisewhere π is the probability of success. Show that n∑i=1Xi is a sufficient statisti
Question
Let X = {X1, X2, . . . , Xn} be a random sample of size n from the geometricdistribution with probability mass function:pX (x; π) ={(1 − π)x−1π for x = 1, 2, . . .0 otherwisewhere π is the probability of success. Show that n∑i=1Xi is a sufficient statisti
Solution
The problem is asking to show that the sum of the random variables, Xi, from a geometric distribution is a sufficient statistic. A sufficient statistic is a statistic that includes all the information in the sample that is relevant to the parameter being estimated.
Here are the steps to show this:
-
First, we need to write down the joint probability mass function (pmf) of the sample. Since the observations are independent, the joint pmf is the product of the individual pmfs. So, we have:
p(X1, X2, ..., Xn; π) = Π_{i=1}^{n} p(Xi; π) = Π_{i=1}^{n} (1 - π)^(Xi - 1) * π = π^n * (1 - π)^(Σ_{i=1}^{n} (Xi - 1)) = π^n * (1 - π)^(Σ_{i=1}^{n} Xi - n)
-
Now, we can see that the joint pmf can be expressed as a function of π and T(X), where T(X) = Σ_{i=1}^{n} Xi, and does not depend on the individual Xi's. This is the definition of a sufficient statistic.
Therefore, the sum of the Xi's, Σ_{i=1}^{n} Xi, is a sufficient statistic for the parameter π in a geometric distribution.
Similar Questions
Let N be a random variable taking values 1, 2, . . . with known probabilities p1, p2, . . ., where Σpi = 1.Having observed N = n, perform n Bernoulli trials with success probability θ, getting X successes.(a) Prove that the pair (X, N ) is minimal sufficient and N is ancillary for θ.(b) Prove that the estimator X/N is unbiased for θ and has variance θ(1 − θ)E(1/N )
Suppose that there are n trials x1, x2,...,xn from a Bernoulli process with parameter p, the probability of a success. That is, the probability of r successes is given by n r pr(1 − p) n−r. Work out the maximum likelihood estimator for the parameter p.
Using the axioms of probability, prove P(𝐴𝑐) = 1 − 𝑃(𝐴)
If we use p to denote the probability of success, and, therefore, 1 − p is the probability of ""
Let X be the number of independent coin tosses it takes to see the first head, where the coin has probability p of landing on its head. That is, X is a geometric random variable with parameter p. a) Use the above characterization to write the probability mass function of X. b) Show that X has the memoryless property: P(X>= k+l | X>=l) = P(X>=k) for every pair of integers k, l >=0. ( This can be done in two ways, one computational, and one via a soft argument.)
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.