# Questions tagged [function]

A mapping between a set of inputs and a set of outputs.

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### Is $f(\widehat{x})$ ($\widehat{x}$ is a random sample of $x$) equivalent to $\widehat{f(x)}$ (a random sample of $f(x)$)? [closed]

Assuming $f(x)$ is an injective function, is sampling $\widehat{x}$ from the distribution of $x$ then calculating $f(\widehat{x})$ equivalent to directly sampling from the distribution of $f(x)$? Note ...
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### Find the relationship among adjusted 3-pointer (not parameter, but formula like Pythagenport, Pythagenpat), goals scored and goals allowed in football

I was seeking a formula to relate goals scored and goals allowed to points. Firstly, I worked with points percentage — points divided by available points, which I set to the number of matches ...
1 vote
35 views

### Is sequence of probability mass functions always uniformly bounded

Say that we have a sequence of discrete random variables, $\left\{X_n\right\}_{n \in \mathbb{N}}$, which converges to a random variable, $X$, with a continuous distribution, e.g., the Normal (Gaussian)...
• 135
1 vote
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### Should 3-pointers be worth 2.5 points?

I was seeking an alternative scoring rule sets instead of three points for a win (gained more engaging and balanced) to cancel the theory "Banking a draw meaning a new kind of loss". It's ...
10 views

### Finding the derivative of the kSVM classifier funcion with respect to the weight vector?

I would like to try a different approach for defining the kSVM. However to do that at some point I need a derivative of the clasifier function $y(\textbf{x})$ with respect to the weights vector ...
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1 vote
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### SMOTE vs Stratified Sampling in highly imbalanced dataset - classification

I am working on a project with the goal of predicting Cerebral strokes from brain arteries data (speed of blood, resistance etc. of one artery and of the neighboring ones). I have a dataset with ...
• 11
26 views

1 vote
33 views

### ML approach to learn function as output

I have a question on how to use ML (machine learning) methods for the following task. I have a m-dimensional (field is always over real numbers $R$) input vector $\vec{x}$, and I want to learn the ...
58 views

### Is there a name for $\sum P(x) \frac{P(x)}{Q(x)}$ ? (P and Q are pmf)

I know that $\sum P(x) log \left( \frac{P(x)}{Q(x)} \right)$ is the kl-divergence. I'd like to know if there is a name for $\sum P(x) \left( \frac{P(x)}{Q(x)} \right)$ (no log), but couldn't find one. ...
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32 views

### Relationship between deterministc function of random variables

Given a discrete $P(X,Y,Z)$ let's call $\Omega$ the set of all deterministic functions $f: XYZ \rightarrow W$ and $\Omega'$ the set of all deterministic functions $f': XY \rightarrow V$. Is it correct ...
• 617
2k views

### Problem with user-written function: "Error in shapiro.test(a) : is.numeric(x) is not TRUE" [closed]

Dear StackExchange community, I am trying to write a function to automate some normality-checks. Here is my try (automates Shapiro-Wilk test, histogram and Q-Q plot creation ): ...
188 views

### How to make the best final prediction of the optimum value in a Bayesian optimization process?

I'm trying to understand the process of Bayesian optimization of a black box function and the bit I'm confused about is how to make the very last prediction of the true maximum after you have made all ...
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1 vote
122 views

### Fitting model to Wood's lactation curve

I'm trying to determine how I can estimate the following model: $y = at^bexp(ct)$, where $a$, $b$ and $c$ are estimate from a set of data. But I can't figure out how to derive the formula into ...
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### How is an 'ogival function' defined?

Reading on a paper on factor analysis and measurement invariance I find the description of some functions as 'ogival' functions. In Google I find it referenced mostly in papers from the '70s and '80s....
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### Calclulating and creating x matrix using set.seed function [closed]

I have been asked to evaluate the sum of xi's? what could be wrong with the following code? How to correct it to work? set . seet (1) #set random seed x = rnorm (50) for ( j in 1:50){ s = s + x [ i ] ...
44 views

### Viterbi Algorithm [closed]

Can someone explain why Is it because for the left argument, we would find the most likely sequence of states given observations and for the right argument, we would eventually find the most likely ...
1 vote
24 views

### A space of functions and their Fourier Transforms?

Conjugate variables and the Fourier transform are often used to analyze different states of a single object. For example in Quantum Mechanics it can be used to describe changing information about ...
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