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1 vote
1 answer
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Variance of sum of deviations

Suppose I have an i.i.d. sample $\{X_i\}_{i=1}^M$ for some positive integer $M$, and suppose that $X_i \sim X$ for some random variable $X$ with finite variance. Then, denote by $$ E_M = \frac1M\sum_{...
G. Gare's user avatar
  • 1,450
0 votes
1 answer
165 views

Upper bound for Variance of linear combination of random variables: $\operatorname{Var}\left(x^Ta\right) \leq \frac{\|a\|^2}{4}. $

I found this while reading a paper where they used it as a casual fact. Say, you have a vector $x = (x_1, x_2, \dots, x_n)$ where $x_i \in [0,1]$ are independent random variables. Consider linear ...
melatonin15's user avatar
3 votes
1 answer
2k views

Cramer-Rao Casella Berger 7.38 for exponential family

The question states ''let $X_{1}, \dots, X_{n}$ be random sample from $f(x \mid \theta) = \theta\cdot x^{\theta-1}$ for $0 < x< 1 ; \theta > 0$. Is there a function of $\theta, g(\theta)$ ...
sophie-germain's user avatar