All Questions

-1
votes
0answers
40 views

Survival analysis in R

My question relates to the answer here: How to plot adjusted Kaplan-Meier Curves?. I can not understand why there is no covariate ("blood pressure") in this code? So, there are 4 groups, they are ...
2
votes
0answers
34 views

Is there a measure of “complexity” for linear/nonlinear model terms?

My apologies if this is grossly misunderstood or mis-worded, but I've been mildly bugged by a question to which I've not found a satisfactory answer. I can't say that I have seen a discussion about ...
0
votes
0answers
9 views

How to compare between multiple factors in GLM

I have read many books and papers comparing GLMS with just a couple of factors with 2 levels, however I am trying to compare whether the presence of parasites differs by month over a 12 month period. ...
0
votes
0answers
15 views

How to statistically infer common pattern in text

Am trying to solve a problem where I need to infer common patterns in text for example, the data below, with bare eyes it can be noticed there is a pattern and that is ...
0
votes
0answers
9 views

Application of Recursive Feature Elimination to Support Vector Machine Model

I have developed a support vector machine model with 78 features on which I would like to apply recursive feature elimination. I developed the model with the package ‘rminer’. fitmodel<-fit(...
0
votes
0answers
9 views

error in information theory

At the risk of sounding vague, someone told me that errors in information theory usually comes in the form of $c/t$, $c/t^{\alpha}$, or $\exp{(-\alpha t)}$, where $t$ is the $t-$ (or $x$ axis). I ...
0
votes
0answers
9 views

Approximating a proxy to the mutual information with Monte-Carlo sampling and Restricted Boltzmann machines

I first asked this in the physics community, to no avail, so now I'm here! I've been reading through Koch-Janusz and Ringel's, "Mutual Information, Neural Networks, and the Renormalization Group" (...
2
votes
1answer
21 views

Efficiently Computing The Beta CDF [duplicate]

I am using numba to JIT compile some looped python functions as part of a larger application. Ideally, everything will run in numba's "no python" mode, such that the loop can be parallelised. One of ...
1
vote
1answer
26 views

Compare two samples with many zeros

We carry out a number of some experiments and got 10 independent 2-samples datasets. Is it possible to show a significant difference between the two samples, if each of them contains more than 75% ...
0
votes
0answers
12 views

Theoretical cdf [on hold]

Is it possible to plot multiple theoretical cdf in one plot using R? I have used the fitdist function in the fitdistrplus package to get both the emperical and theoretical cdf. Using cdfcomp() gives ...
0
votes
0answers
18 views

How to find maximum probability [on hold]

Members of a mafia group gathered at a secret hideaway. The city police come to know about the meeting and plan to arrest the leader of the group. The police know that the members of the mafia will ...
0
votes
0answers
7 views

Time series analysis. Showing stationarity and acf [on hold]

Consider an at(2) process given by xt=1/4x(t-1) + 3/4 x(t-2) + et. Show that its stationary and hence find it's act
0
votes
1answer
16 views

Modelling enzyme reaction kinetics in R

I have a simple data set with three experiments, three replicates each, measurements of enzyme activity performed at concentrations of an enzyme of 0, 1, 10 and 100. Is there a standard way, ...
0
votes
1answer
18 views

Extract some columns from different two dataframes by matching dates in a range of 30 minutes [on hold]

I have two different data frames. First one has 14 columns and 255k rows. Second one has 18 columns x 6150 rows. First columns of both data frames are dates in POSIXlt ("%Y-%m-%d %H:%M"). The ranges ...
0
votes
1answer
11 views

Model with lower no of layers is getting better performance than standard models

Hi Everyone I am a beginner in deep learning. I am doing my research work in deep learning. The topic on which I am working is Skin cancer image classification. I have tried training various standard ...
2
votes
1answer
12 views

Unsupervised clustering of sequence of events to subsequences

I have a big dataset of M sequences of [1 - N] events, where each event has multiple properties (start date, end date, location, ...
0
votes
0answers
13 views

Does this decomposition theorem of stationary process exist?

I have this vague impression that there was a theorem on Wikipedia about stationary process, saying that if $(x_k)$ is a strictly stationary process, then there exists a decomposition in the form of $...
-1
votes
0answers
8 views

Bokeh glyphs AnnularWedge HELP! [on hold]

I used Bokeh to visualize my data. Anybody know how i can display a cloud of points in the forme of AnnularWedge ???? Tks so much
6
votes
2answers
119 views

Expectation of inverse of sum of positive iid variables

Let $(X_i)_{i}$ be a sequence of iid positive variables of mean 1 and variance $\sigma^2$. Let $\bar{X}_n = \frac{\sum_{i=1}^n X_i}{n}$. My question is: Can we can bound $\mathbb{E}(1/\bar{X}_n)$ as ...
1
vote
0answers
13 views

Software Financial Performance [on hold]

Which software is the best to evaluate on company financial performance? Currently I'm working on financial analysis for my company performance. It was quite confusing to see a variety of software ...
0
votes
0answers
13 views

Mistakes due to extrapolations [on hold]

I wanted to ask if there are any famous examples of people/scientists mistakingly extrapolating past data points into the future leading to bad consequences?
1
vote
0answers
18 views

Violation of proportional hazard assumption with big sample size - how to correct for it?

I am looking at a sample of about 95,000 firms in Switzerland and I want to find out if having an external auditor (such as PwC, KPMG, EY) reduces the likelihood that a firm goes bankrupt. In ...
1
vote
2answers
28 views

Why z-score/standard score is a linear transformation

Can someone please help me understand why the standard score $(X - \mu)/\sigma$ is a linear transformation since both mean and standard deviation depend on X?
0
votes
0answers
6 views

Permutation F test for nested models

How can I do a permutation F test for testing if a larger model which contains a larger model is better? e.g. Model 1 : y ~ x1 + x2 Model 2 : y ~ x1 + x2 + x3 + x4 H0 : beta_3 = beta_4 = 0 H1 : ...
0
votes
0answers
9 views

Classification with dependent target

Let's suppose that my data set has the following structure: ...
0
votes
0answers
2 views

Help: Null Values for penalized SVM

I am interested in fitting a SVM model to my data with Elastic SCAD penalty. I was trying to use the penalizedSVM library for this. The issue is that for some reason, the library outputs a null model ...
0
votes
0answers
7 views

How to calculate ± deviation for precision and recall?

I found a precision and recall report table like as below Precision Recall .470±.009 .934±.013 .239±.010 .610±.013 I need the guidelines for ±.009 and ±.013 ...
0
votes
0answers
4 views

Synthetic Control Method with Correlated Variables

I am interested in using the Synthetic Control Method to measure the effects of a certain policy. I am afraid that the synthetic control will not be accurate because the underlying variables that make ...
0
votes
0answers
5 views

Exact definition of very short term load forecasting(VSTLF) and short term load forecasting(STLF)?

In the research papers, I have read that VSTLF is for minutes and hours ahead, whereas STLF is for days and weeks ahead. However, If I do a week ahead prediction of load data with a 5 minute ...
0
votes
0answers
3 views

Ranking the conditional probability of classification study (PLSDA) to get better accuracy

I am building a model to predict the probability of an animal to be poor or good, using PLSDA. The sensitivity and specificity are 76% and 56%, respectively. Let's ignore the sensitivity for now, ...
0
votes
0answers
13 views

Iteratively Reweighted Least Squares Poisson Regression with Non-Canonical Link, eventually in R

I am attempting to implement iteratively reweighted least squares (IRLS) for a poisson regression with a non-canonical link function. My understanding of IRLS is only basic at this point, so please ...
0
votes
0answers
27 views

Sufficiency of $|X|$ when $X\sim N(0,\sigma^2)$ without using Factorization theorem

Question: Given, $X\sim N(0,\sigma^2)$. By means of conditional approach show that $|X|$ is a sufficient estimator for $\sigma^2$. My Attempt: This problem is very easy if we use Fisher–Neyman ...
0
votes
0answers
13 views

panel IRF and FEVD from panel vector autoregression in r

The package panelvar in r can estimate panel vector autoregression models. It can also produce IRFs and FEVDs the aggregate endogenous variables. How can I get IRF and FEVDs for panel units/...
0
votes
1answer
12 views

How to determine mse of estimate from correlation matrix of estimate error?

I have a model of an information transmission system Y = XH + N, where X is a diagonal matrix with the transmitted "symbols" (known), H is a column vector which distorts the transmitted symbols and N ...
1
vote
0answers
6 views

Lottery entry for convention panels - grouping vs going solo

The upcoming Star Wars convention in Chicago is testing out a new system that allows people to enter a lottery to try and get a seat at the big panels. This has lead to a lot of math and pseudo math ...
0
votes
0answers
6 views

Measuring relative variability for variables with different scales II

I'm reformulating this question to see if I might have better luck than OP did at encouraging a response. Consider that you have two univariate datasets at different scales, and need to establish ...
0
votes
0answers
4 views

Ways to compare Likert ratings with non-equal total response count

I have Likert response data like this in which the surveyor asked 188 raters to rate on a 1-5 Likert scale for 6 different stories with the question, "I'd like to hear more stories like this". Some of ...
0
votes
1answer
27 views

Could confounding factors unmask a significant relationship?

Suppose we have one dichotomous dependent variable and ten independent variables ( mix of categorical and continuous), by using a $t$ test and a $\chi^{2}$ test no relation was found between each ...
0
votes
0answers
18 views

Difference in model performance measures of train and test data sets

I am using CART classification technique by dividing a dataset into train and test sets. I have been using Mis-classification error, KS by rank ordering, AUC and Gini as MPMs(model performance ...
0
votes
1answer
46 views

Bayesian Decision theory

A person randomly chooses a coin with probability 0.5: Tossing coin 1 yields a head with a probability P(X1=H)=.3 (and tail with P(X1=T)=.7). Tossing coin 2 yields a head with a probability P(X2=H)=.6 ...
0
votes
0answers
13 views

Does High Dimensional Data effects SVM?

As we move into higher dimensions, we will find even more corners. This will make an ever increasing percentage of the total space available. Now imagine we have data spread across some ...
2
votes
1answer
51 views

Ridge Regression with Gradient Descent Converges to OLS estimates

I'm implementing a homespun version of Ridge Regression with gradient descent, and to my surprise it always converges to the same answers as OLS, not the closed form of Ridge Regression. This is ...
1
vote
0answers
24 views
0
votes
0answers
11 views

Predicting Transformation

One of my friends found the paper An Empirical Analysis of Feature Engineering for Predictive Modeling. We were discussing the models the author wrote about. He wrote: If the machine-learning model ...
0
votes
0answers
25 views

Smoothing splines as basis expansion

I am following the discussion on chapter 5 of Elements of statistical learning which discusses basis expansion using splines. The data set I used is the Ozone data which can be found at :http://web....
0
votes
1answer
31 views

What would be the output distribution of ReLu(X) activation (In case that the distribution of X is unknown)?

Suppose E[X]=0, var(X)=1 and we know X has a symmetric distribution, What would be the distribution of 𝑌=ReLU(𝑋)=max{0,𝑋}? I have seen this question What would be the output distribution of ReLu ...
0
votes
0answers
6 views

Should stratified cross-validation be used in a regression context?

After a number of Google searches and looking at various stack posts, I cannot find much information or discussion about using stratified cross-validation in regression context. I am modeling forest ...
1
vote
0answers
9 views

Overidentified vs just identified models

Why go with overidentified models as opposed to just-identified? If you can go with over-identified models, how many instrumental variables can you have at max in a 2SLS model?
0
votes
0answers
12 views

Instrumental variables - alternatives to 2SLS: not using exogenous variables in the first stage

I think that everyone knows how 2SLS works. say that we have: $y_t=a_1 +a_2X_t+a_3W^1_t+a_4W^2_t+e_t$ Let's call this equation equation (1), where $X_t$ is an endogenous ...
0
votes
0answers
14 views

What is the point of a bias in this model [on hold]

I'm taking a look at this stan code: https://github.com/stan-dev/example-models/blob/master/bugs_examples/vol1/seeds/seeds.stan I am unsure as to the purpose the ...

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