Questions tagged [iid]
iid is an acronym for independent and identically distributed. Many statistical methods assume that the data are iid; that is, that each observation comes from the same distribution and is independent of other observations.
255 questions
6 votes
2 answers
489 views
How to test i.i.d. assumption?
Given a sample $X_1,\ldots X_n$, how can I test the hypothesis that these are i.i.d. samples from a fixed (unknown) distribution? To add context, assume this is a time series and I want evidence ...
4 votes
1 answer
217 views
Do i.i.d. assumptions extend to datasets of independently generated sequences in modern sequence models (e.g., RNNs)?
In standard machine learning settings with cross-sectional data, it's common to assume that data points are independently and identically distributed (i.i.d.) from some fixed data-generating process (...
3 votes
1 answer
170 views
Is Copula Modeling Suitable for Accounting for Temporal Dynamics in Olive Plantation Data?
I am working on a project analyzing olive plantation data, where I aim to simulate the relationship between investment costs (Costs), revenues (...
0 votes
0 answers
26 views
Variance of product of multiple i.i.d. random variables? [duplicate]
Definition: Random variables X1, X2, ..., Xn are said to be independent and identically distributed (i.i.d.) if they are independent, and they have the same marginal distributions: FX1(x)=FX2(x)=...=...
0 votes
0 answers
36 views
Product of iid random variables contradiction [duplicate]
I was working through some econometrics problems, and my professor used the result that the product of iid random variables is iid, but I've seen some posts that this might not always be the case. My ...
0 votes
1 answer
211 views
Expected value of iid squared conditioned on sum
I would be interested in finding the value of the following expression: $$\mathbb{E}[X_k^2\mid S_N]$$ where $X_k$ are iid random variables with $\mathbb{E}[X_k]=\mu$ and $\operatorname{Var}[X_k]=\...
0 votes
0 answers
68 views
Are $X_i \varepsilon_i$ iid?
Take: $X_i , \ i = 1, ... , n $ iid. $\varepsilon_i , \ i = 1, ... ,n$ also iid. $X_i \not \perp \varepsilon_j$ (they are not necessarily independent) Are $X_i \varepsilon_i$ iid ?
4 votes
1 answer
530 views
Link between Cross-entropy and MLE
There are numerous material that show the relationship between MLE and cross-entropy. Typically, these are the steps taken to show the relationship for a I.I.D data generating process $D = (X,Y)$: $$ ...
13 votes
6 answers
2k views
Why GLM doesn't have an error term and why shouldn't residuals be i.i.d?
I've read dozens on post on the subject but I cannot figure this out. From what I've gathered, GLMS don't include an error term in their formulation unlike linear models (LM). I was wondering why (or ...
0 votes
0 answers
57 views
How to understand intuitively the CDF formula for the maximum statistic of three iid rv’s? [duplicate]
Given that all three iid rv’s ($X_1, X_2, X_3$) have CDF $F(x)$, the formula for the CDF $G(y)$ of the largest rv ($Y=X_i$) among the three is: $G(y)=P(X_1 \leq y) \cdot P(X_2 \leq y) \cdot P(X_3 \leq ...
0 votes
0 answers
57 views
Method-of-moment of n IID random variables
The method-of-moment of $\sigma$ for the following pdf is $$ \text{pdf}(x,\sigma) = \frac{x}{\sigma^2}\exp(-\frac{1}{2}\frac{x^2}{\sigma^2}) $$ $$ E[x] = \int_{0}^{\infty}\frac{x^2}{\sigma^2}\exp(-\...
1 vote
0 answers
71 views
Is it possible to describe repeating data patterns as a stochastic process?
Generally, can repetitive patterns in sensor readings (e.g. temperature measurements at different locations over time) be seen as some kind of stochastic process? That is, if similar patterns repeat ...
1 vote
1 answer
146 views
Is the Distribution of Survival Times always IID?
I was reading about an approach to Survival Analysis called "First Hitting Time Models" (threshold regression): https://www.jstatsoft.org/article/view/v066i08 , Can Survival Models model the ...
0 votes
1 answer
208 views
Misunderstanding on the use of Popoviciu and von Szokefalvi Nagy's inequalities on the variance of a unbiased estimator
Let $X_1,\cdots,X_n$ be (discrete in my case) i.i.d. and bounded between $m$ and $M$. I'm interested in bounding the variance of an unbiased estimator: $$\mathbb{V}\left[\frac1n\sum_{i=1}^nX_i\right]$$...
1 vote
0 answers
93 views
If $X_1, \dots, X_n$ iid, are $f(X_1), \dots, f(X_n)$, also iid? [duplicate]
If I have independent and identically distributed random variables $X_1, \dots, X_n$, then are $f(X_1), \dots, f(X_n)$ themselves independent and identically distributed? I think the answer is yes, ...