The mathematical concept of a function. See http://en.wikipedia.org/wiki/Function_(mathematics)

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19 views

Is there any argument in GAM function (R software) to tell the model which variables are categorical or continuous? [on hold]

I want to fit a species distribution model for some bat species using a generalized additive model (GAM). I have 124 presence points and I generated 10000 random absence points. I also have 18 ...
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0answers
21 views

Algorithm to identify a correct input for only one number [on hold]

Hello I'm hoping that you good folks here at CrossValidated can help me with this. I'm looking for an algorithm that takes an integer as an input and returns two types of values. One type of value ...
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0answers
27 views

Implication of Hazard Rate?

So from my understanding, the hazard rate is not a probability but a rate of an event happening at any one period of time. Can someone please tell me the implications of a hazard rate value. Would ...
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1answer
19 views

Learning a spatial function

I have some observations of a variable y, that varies spatially. For each observation, I also have a lat, long tuple. I have some 50 or so observations. Besides conducting some exploratory analysis ...
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2answers
65 views

Apply function generating random numbers to a matrix (R) [closed]

I have a function which basically creates a random number. Now I want to apply the function to a matrix for given conditions to replace the value in the matrix with the random number created by the ...
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60 views

What function best describes this plot?

The X and Y have values only between 0 and 1.
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1answer
53 views

Find distribution of underlying feature

Let's say I have a dataset with values for the variable $W$. The distribution of $W$ doesn't follow any obvious known distribution. I have a model that gives $W$ as a functions of $E$ and $K, W = ...
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35 views

Using A Time Series To “Scale” Another

I know the "average theoretical cost per impression" for Jan 13 - Dec 13. I have other monthly time series for "total # of impressions", "total # of clicks" and "total number of conversions" for Jan ...
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31 views

Calculate pdf of complex model

I'm trying to model the distribution of effects of mutations (let's call it s) in evolution but I'm stuck in generating the probability distribution function (pdf) for my model. So, my model is a ...
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1answer
52 views

What is the name of the resulting function?

Consider the following population regression model: $$y_{i} = \beta _{1} + \beta_{2}x_{i} + \epsilon _{i},$$ where $i=1,...,n$. Assume $\epsilon \sim iid$, with the pdf in equation: $f(\epsilon ) = ...
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19 views

Validating sameness or difference of a relationship

I am measuring a response variable Y(x,t) which theoretically is a function of both time (t) and space (x). I have measurements for Y as t varies for different spatial points x. On inspecting visually ...
2
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1answer
78 views

Time Series Function - Constant vs Piecewise

I have daily data for online marketing $ spend and the number of clicks to the website gained. I want to determine a function that 'maps' the two together. I cannot use normal linear regression ...
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0answers
13 views

Tendency tags based on series of numbers

I am trying to create tendency tags based on historic data. Ie, I have the following series always ordered in time: [w,x,y,z] where: ...
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2answers
49 views

Can you compare probabilities of an epidemic by knowing R0 values?

In comparing two diseases with different basic reproduction numbers (R0), is it possible to use the R0 values to calculate the probability of an epidemic spread through a population? For example, if ...
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0answers
28 views

Why SVM with RBF is similar to KNN with prototypes search?

I explored similar questions and everything I can see is that both kNN and RBF are non-parametric methods to estimate the density of probability of your data. However, I am not sure if this has ...
2
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2answers
62 views

What is this formula?

i have been asked to plot a graph of the residuals from the following formula: |y(hat)/y|-1 they said that it was MAPE but i have the formula for MAPE as: ...
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0answers
23 views

How can you cluster a set of functions with unknown functional forms?

Say you've $N$ functions $f_N(x)$ defined on a regular grid $x$. You don't know the form of $f(x)$, you've only got several realizations of it. The different functions are related to each other ...
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0answers
16 views

Web page scoring function based on readability (LIX)

I'm creating a scoring system for web pages based on their level of readability using LIX. A selection of pages from a web site are crawled and given a score. Besides average and median, what ...
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1answer
51 views

Correct notation wrt. uniform distribution

Assume that I have a discrete set $L$ and a transformation $\phi: L \rightarrow [0,1]$ that normalizes set $L$ such that now values belonging $L$ are uniformly distributed among the unit interval. ...
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0answers
22 views

How to represent this problem in a useful way?

How can I represent this problem as a function. Bear with me because it may seem odd. Say, for example I make cakes. There are 30 variations of cake in one batch. For each batch there are 19 luxury ...
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1answer
81 views

Generating functional-form PDF from Max Likelihood Estimation

For the purpose of this question, please consider me a stats newbie. I'm working on a (very fun!) research project which involves estimating a pdf of "personal values" -- i.e. how much a certain ...
2
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1answer
60 views

Given the distribution of a variable X, what is the distribution of f(X)?

Suppose I know the mean and standard deviation of a (roughly) normally distributed variable x. Is there any way for me to calculate the mean and standard deviation of f(x)? The particular problem I ...
0
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1answer
89 views

dealing with exponentials in python - infinities and overflows [duplicate]

In a machine learning algorithm that I'm using, I need to get the exponential values of something in one of the steps. This is the step that I'm dealing with right now: I've already got all the ...
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0answers
30 views

Is $Max${$F(X),G(Y)$} necessarily a distribution function?

If $F(X)$ and $G(Y)$ denote two distribution functions, then is $Max${$F(X),G(Y)$} necessarily a distribution function as well?
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47 views

How to interpret basis function that yields vector in machine learning algorithm?

I'm struggling to understand what $\phi(x_{N+1})$ is in this excerpt of an algorithm (namely Linear Bayesian Regression embedded in other algorithm): $c_i = \gamma_i / \sum^L_{j} \gamma_j$ ...
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0answers
23 views

Rearranging 2 discriminant function to solve for 1 parameter (to derive a decision boundary)

I have a task where I want to classify patterns from 2 classes where the samples are drawn from a bivariate Gaussian distribution. I use the 2 discriminant functions ($g_1$ and $g_2$) to classify the ...
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2answers
191 views

How to properly handle Infs in a statistical function?

Suppose I have a function such like: f <- function(x){ exp(x) / (1 + exp(x)) } it's supposed to work for any real value of x, but actually it returns NaN ...
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2answers
588 views

Difficulty with auto.arima function results

I am new to R and the ARIMA model and I am attemping to forecast 1440 values into the future using a base of roughly 5000 numbers. It is data extracted roughly every minute from a machine ...
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2answers
54 views

cumulative distribution function , cdf problem

I cannot understand how step 2 transformed to step 3, anybody help me please ???
2
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1answer
194 views

Calculating power function for ANOVA

There are several functions in R to calculate the power of a test, for example, the pwr-functions of the pwr package. My question is how we get this function for ...
0
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1answer
50 views

Gradient without function, just testing and training data

I am new to optimization in particular so I think what I am looking for is vocabulary to describe a particular area of problems. In many (all?) optimization algorithms you need to take the gradient of ...
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1answer
387 views

Function to find the quantile in a vector corresponding to constant $x$ [closed]

Suppose I have constant x=0.1 in the language R and I have a vector vec = rnorm(200). Is ...
7
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2answers
242 views

Function of random variables

I am not sure what the right keywords would be for this but I would like to know if it is possible to apply functions to random variables. I think it may make sense in terms of expected value but I ...
1
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1answer
268 views

R - Calculate trendline and extend it for 365 days automatically

I have daily data with logarithmic decreasing trend (around 30-days-data). In excel I'm calculating these data's trendline and with that trendline equation, I'm projecting these values to 365-days ...
2
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1answer
42 views

Requirements for evaluation function in evolutionary algorithms

For a publication I'm looking for references for generic requirements of evaluation/fitness functions in evolutionary (more specifically genetic) algorithms. I could come up with some requirements ...
0
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1answer
97 views

Can I derive the PDF ( f(C) ) from a spatial function defined as C(x)?

Say I have a random variable (such as concentration) that is defined spatially by some function $C(x)$. I would like to derive a PDF $(f(C))$ from the concentration function $C(x)$ over some domain ...
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1answer
310 views

Finding the similarity between two functions

I am a first-year grad student in Computer Science, and I need some help with a problem that I think is statistically oriented. I have taken a statistics course, but it was abysmal and I haven't had ...
1
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1answer
125 views

Cumulative function to probability density function

I have some data points for which I would like to show the density using Python, but the package SciPy is not working for Python 3.3. I am looking for a solution to be able to plot some data in the ...
3
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1answer
324 views

R: Defining a new continuous distribution function to use with Kolmogorov-Smirnov Test

I wish to run the Kolmogorov-Smirnov test on my data to determine how well it conforms to a specific continuous distribution function I have in mind. If my understanding is correct, the ...
1
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1answer
688 views

calculation of correlation time?

I have two time series of a two realizations of a random process, the process fluctuate around an average so i consider that is a ergodic process. I compute the time correlation function, but i need ...
0
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1answer
93 views

Can I represent a non-boolean function with a TREE?

I have a question in respect to tree representation of a non-Boolean function. Is there any problem in representing a function from space Boolean->Limited Integer or Limited Integer->Limited ...
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0answers
83 views

Question related to binomial distribution

Let $X \sim Binomial (n, p)$ with both $n$ and $p$ known. Suppose for some non-increasing function $G:[0,1] \rightarrow [0,1]$, and some fixed $c_0 \in [0,1]$, we have that \begin{align} ...
9
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2answers
359 views

How to estimate the accuracy of an integral?

An extremely common situation in computer graphics is that the colour of some pixel is equal to the integral of some real-valued function. Often the function is too complicated to solve analytically, ...
6
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1answer
760 views

Proof that if higher moment exists then lower moment also exists

The $r$-th moment of a random variable $X$ is finite if $$ \mathbb E(|X^r|)< \infty $$ I am trying to show that for any positive integer $s<r$, then the $s$-th moment $\mathbb E[|X^s|]$ is ...
3
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1answer
169 views

Objective function in linked prediction models

I would like to use R “optimize” function to estimate the model: $\hat{Y_{t}}=a\cdot \hat{Y}_{t-1}+b\cdot X_{t}+c\cdot X_{t-1}$ Important thing is that the predition $\hat{Y_{t}}$ (let’s say ...
0
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0answers
155 views

Posterior mean of exponential functions: how to do it with MCMC?

I am struggling with estimation of posterior mean of simple exponential function f(x)=exp(x). Mixing of the chain is quite good and there is no problem with estimation of simple mean, but since ...
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3answers
239 views

Find a mapping of two probability mass function to another probability mass function

Lets' $p$ and $q$ are probability mass functions of two discrete random variables. I need examples of functions $F(p,q)$ that $r = F(p,q)$ and $r$ is a probability mass function for some random ...
5
votes
1answer
661 views

In spatial regression, what is a spherical autocorrelation structure?

I have a large gridded dataset for the globe (i.e a spherical, wraparound surface) that I'm applying spatial regression to (using a CAR model). I've been using the default autocorrelation function, ...
9
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1answer
362 views

Proving a sequence decreases (supported by plotting a large number of pts)

Many of the questions I've posted on SE in the last month have been in the goal of helping me solve this particular problem. The questions have all been answered, but I still can't come up with a ...
2
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0answers
141 views

Estimating the x-intercept of an arbitrary monotonically increasing function

I have a continuous monotonically increasing function, $f(x)$, whose $x$-intercept, $x^*$, I am trying to estimate. I have a dataset of $(x_i,y_i)$ pairs, with each $y_i=f(x_i)+\varepsilon_i$, where ...