# All Questions

0answers
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### “Likelihood Ratio” for multiclass

If i have 2 classes, the likelihood ratio gives me a boundary like the image below. What if i have 3 or more classes ? What test can I use to classify an input data ? What if it is a mixture of ...
1answer
3 views

### Feature selection vs PCA vs the Intuition?

which one should i choose? how can i combine them (i.e. in series or in parallel)? what if there are dummy features in my data?what if my Intuition missed things up?
0answers
6 views

### What explanation can i give for having a negative correlation coefficient but positive regression coefficient? [duplicate]

The first table is the regression results showing negative correlation coefficients for all variables. However in the regression table below, only EXR shows the same association as the correlation. ...
0answers
4 views

### Does shapiro.test use the Rahman-Govidarajulu extension?

I was just by chance confronted with an odd inconsistency. The Wikipedia Page on the Shapiro-Wilk test suggests the original Royston algorithm is maxed out at a sample size of 2,000. ...
1answer
6 views

### large sample and significance

I have a very large sample (790 million rows), and in this case, even small difference are determined to be significant, p <0.0001. The 95% C.I.s are very sharp. In this case, these tests (t-test, ...
1answer
7 views

### Is there a concern for multiple comparisons when ranking instead of using significance?

Let's say I have many ANOVA tests on the same data using different factor variables each time. Then, I want to rank the F-statistics for all of those tests. Notice that I'm not interested in ...
0answers
4 views

### How to determine counts of viruses from limiting dilution assay

My question relates to a common experiment in the field of virology. Let me give some background so you understand why I'm asking this question. When producing virus for an experiment you typically ...
0answers
9 views

### What is the difference between the Monte Carlo Method in R package 'DMwR' and a normal Monte Carlo Method?

I am trying to estimate the performance of a machine learning model on time series data. I saw the example of model evaluation using Monte Carlo Estimates from the book "Data Mining With R Learning ...
0answers
12 views

### Using confidence intervals with Simple Linear Regression

So simple linear regression is performed on 3000 data points, and 1000 data points are withheld. How can we use confidence intervals, along with the withheld data points, to assess the predictive ...
1answer
7 views

### Generalized Hurst Exponent - What value to specify for $\tau_{\max}$?

Consider a time series $X: S \to \mathbb{R}$, where $S := \{\nu, 2\nu, 3\nu, \ldots T\}$, and $T$ is a multiple of $\nu > 0$. For each $\tau \in (0, \tau_{\max}] \cap S$ and $q \in \mathbb{N}$, ...
0answers
6 views

### how to achieve function criterion to be close to zero [on hold]

I wrote this R script to solve solve this system of nonlinear equations using nleqslv package. ...
1answer
4 views

### How does DeepMind's DQN agent determines target values for sampled episodes?

In DeepMind's paper titled Human-level control through deep reinforcement learning authors present Algorithm 1 (available in the paper reachable with mentioned link) for training of deep Q-learning ...
0answers
3 views

### Modelling a Static Bayes Net versus Dynamic Bayes Net

I have a Bayes Net with 20 variables, but I found out that one of the Parent variables is dependent on the previous value of its Child as: C(t-1)->P(t)->C(t) C and P are binary (True or False). All ...
1answer
11 views

### Finding subset of data where the 'B' in A/B testing is true

Suppose that I have implemented a referral program in my product, in which I offer rewards to a user whenever one of their referrals uses my product. Say, we reward him with gift/prize 'A'. I am also ...
0answers
4 views

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### Difficulties fitting a Cox PH model with categorical interactions to complex survey data

I'm attempting to fit a Cox proportional hazards model to a set of NHANES data; the code to load and clean the data is here, and the resulting dataset is here. The difficulty I'm having is ...
2answers
12 views

### Scaling predictors in ARIMA model

If a predictor in an ARIMA model has much lower magnitude than the variable you are trying to predict, then do you need to multiply it by a scalar in order for it to be an effective predictor in the ...
1answer
31 views

### AICc is picking overly complex models - something stricter?

I'd like to know if there are "stricter" alternatives to automated model selection than AICc / AIC / BIC. We have approximately ten thousand curves, and for each we'd like to find the most ...
0answers
9 views

### Interpreting PCA results on gene expression data

I'm working on a gene expression dataset from patients who either have systemic sclerosis or not. I normalized the data with housekeeping gene values and scaled the expression values for each DNA ...
0answers
5 views

### Normalization of data between 0 and 1, using the ecdf function in MATLAB [on hold]

I would like to normalize/transform data in a variable x such that the new variable y contains values between 0 and 1, computed according to the empirical cumulative distribution function of variable ...
0answers
12 views

### Number of Exponential Summands in fixed interval is Poisson

What is the most clever way to prove that the number of independent exponential summands in a fixed interval is distributed as a Poisson random variable? I can do it one way, but I would like to know ...
0answers
11 views

### More than one output neuron firing [on hold]

I am building a neural network to solve a multi-class classification problem. Is it possible for more than one output neuron to fire?
0answers
6 views

### Understanding output from Survival Analysis(Cox's Regression)

I am using SAS to run Cox's regression.There is a keyword "survival=" which supposedly gives the estimate of survival function. As far as I understand, the survival function is dependent on time and ...
0answers
8 views

### two samples comparison with cyclic variables

How to check if two samples are from the same distribution, when the variable is cyclic? A simple answer for non-cyclic variable is the Kolmogorov-Smirnov test. What is the equivalent for cyclic ...
0answers
5 views

### Partial R2 for regression containing both linear and quadratic terms

I’m trying to get an idea of whether age or rate of aggression in my study species explains more of the variance in cortisol level across individuals. I already know that the relationship between age ...
0answers
15 views

### Why do VAR forecasted values radically change depending on which month historical data end?

I am building a model to forecast housing variables using vector autoregression. I am encountering spurious results. My forecasted values change dramatically depending in which month the historical ...
0answers
39 views

### Sampling from $f(x)$ given approximation $g(x)$

Suppose you want to draw samples from an (unnormalized) pdf $f(x)$, $x \in \mathbb{R}^d$, $1 \le d \le 20$, which might be expensive to compute, and you have a (normalized) pdf, $g(x)$, which is an ...
0answers
10 views

### How to inferring the casual relation between two point processes? Edit

I have two point processes. One is the spike time of a neuron and the other is when a rat licks the sugar water. I want to find out if there is any correlation and causation between these two ...
1answer
5 views

### How to normalize and compare growth rates between variables at different stages of some kind of growth model “curve”?

I have a data frame that has various capital and metropolitan cities with various economic, market and performance data. One set of variables is each total annual non-domestic visitor volume and the ...
1answer
25 views

### Learning from clicks on Ads [on hold]

I need to build an algorithm that predicts the number of clicks a facebook ad would get in the next 7 days. Based on the given requirements, I prepared a dataset consisting of the following ...
0answers
13 views

### Achieve multiple random effects and interactions with lme4 in R

I am trying to replicate a mixed effect analysis where the authors claim that they used the following scheme: Fixed effects treatment, year of observation Random effects block, interaction ...
0answers
15 views

### How to plot a vglm/propodds regression in R

Hi I'd like some help plotting the following regression in "r": fit1_usesrp <-vglm(rp ~ is.native + is.male + oh + cjs + age2 + tw ,propodds, data = dummydata ...
0answers
7 views

### Non-linear least square minimization using for three-dimensional data [on hold]

I have a 3D data and I would like to fit a non-linear model to the data using lmfit. This is the code I have written but it doesn't work. ...

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