# All Questions

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### Sample size in the Latin Hypercube simulation to calculate P90, average and P10 and number of variables relation

I am preparing some simulations to determine the P90, average and P10 of a parameter. How many runs do I need to have to get a reliable answer (let's say 5% margin of error and 95% confidence)? It ...
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### Sample Mean and Sample Standard Deviation [on hold]

How do I calculate sample mean from the question like below: A company has following samples of leaking goods with gaps 0.290, 0.104, 0.207, 0.145, 0.104,0.124. I couldn't understand the question ...
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### Recaculating control limits when an out of control situation is displayed

When plotting control charts if a point plots outside the control limits then the reason for that point to plot outside is checked and if an assignable cause is found to be the cause then after ...
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### Imputing using CFA for use in a Cox regression

I am using CFA (confirmatory factor analysis) to create a measurement model of social capital that is to be used in a Cox regression. Because of missing data I first impute the incomplete data by MICE ...
10 views

### Moderating a curve [on hold]

I have a paper that has a main relationship with a negative curve. It actually looks like a left leaning hockey stick. We have three moderators - two that strengthen the negative slope and one that ...
7 views

### How to test composite hypothesis for the linear regression model

I want to test $H_0:\beta_1>0,\beta_2=\beta_3=0$ in the model $Y = \beta_1x_1 +\beta_2x_2 + \beta_3x_3+\epsilon$. How can I do this?
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### Grid search error in LIBSVM while optimizing C and g parameters

I am using libsvm for a one-class classification problem. I am trying to select the ideal C and gamma parameters for different kernels(polynomial, linear and rbf) I am using the suggested matlab code ...
44 views

### What coefficients do I use for a binomial distribution problem?

I'm studying for an exam and my study guide explained combinations, permutations, and binomial distributions, but didn't cover much how to recognize where each comes into play in problems. I'm having ...
22 views

### What are the various basic kernels available?

I am currently following the book Gaussian Processes for Machine Learning by C.E. Rasmussen and C.K.I. Williams and I have come across various kernels in their Chapter 4 I have also gone through the ...
23 views

### Why does NSDIFFS (R forecast package) never show seasonality? [migrated]

I've been using the EViews statconn DCOM interface to loop a large number of series from FRED through the nsdiffs(test=c("ch")) function in the forecast package of R to examine what percent of them ...
36 views

### What are the parameters of a Wishart-Wishart posterior?

When infering the precision matrix $\boldsymbol{\Lambda}$ of a normal distribution used to generate $N$ D-dimensional vectors $\mathbf{x_1},..,\mathbf{x_N}$ \begin{align} \mathbf{x_i} &\sim ...
29 views

### Is high AIC a bad feature of the model?

I have a model with AIC equal to 78 809. Does this mean this is a very bad model or the intepretation should be different? There are 15 variables, 2-level response variable and 40 000 rows. ...
27 views

### Simulating a data generating process

Suppose I wanted to simulate the data generating process of a non-linear regression with ma(1) errors. So, without going into many unnecessary details, the model is y_t = f(x_t,x_t-1,..., x_{t_0}, ...
109 views

### Linear independence vs statistical independence (PCA and ICA)

I'm reading this interesting paper on application of ICA to gene expression data. The authors write: [T]here is no requirement for PCA components to be statistically independent. That is true, ...
30 views

### How to standardize text data for training Neural Networks?

I want to train neural network with text data(natural language) as input for classification purpose. One way for standardizing text data for neural network is to use N-GRAM/SKIP-GRAM representation ...
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### How to plot ROC curve after using SMO classifier in weka? [on hold]

I classified my data using SMO function in weka. The ROC plot that I got is not a curve (it is based on just one threshold). can anyone help me to plot ROC curve for more decision threshold? how can ...
23 views

### 2 factor factorial model with random factors

Using lme4, how does one define a full 2-factor factorial model with both factors (and their interaction) being random? Specifically I am trying to recreate the ...
11 views

### Regarding post pruning in decision tree

Just 2 issues: 1) what should we do say for example we get 5 Yes and 2 No for a single final leaf node attribute? 2) How to post prune using Chi square test?
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### Multi-signal coherence test

Is there an accepted measure for multi-signal coherence? The signals are time-domain EEG voltage readings from various parts of the scalp. I was working with magnitude-squared coherence, but it only ...
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### Anyone knows how to make a LSTM layer that is able to be trained with arbitrary BPTT time steps and easy to be stacked together?

Anyone knows how to make a LSTM layer that is able to be trained with arbitrary BPTT time steps and easy to be stacked together? I am now implementing a basic version of LSTM layer. My scan function ...
19 views

### How can we compute cumulative change rates for time series data? [on hold]

Take the annual precipitation data for some area from 1960 to 2008 as an example. How can we compute cumulative change rates for such data?
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### Is there a correlation index for Binary Variable vs Quantitative variable?

I know that I can use a logistic regression model to test if quantitative variables influence the binary variable, but I would like to have an Index, like Pearson correlation index to tell how strong ...
43 views

### Product of two gaussian processes

Given, $\ {y}_{i} = N({\mu}_{i}, {\Sigma }_{i})$ If we go by the link http://www.tina-vision.net/docs/memos/2003-003.pdf then we can understand that the product of many multivariate gaussians can ...
6 views

### Is there a general structure for papers/documents explaining computer vision databases?

I recently created a database of images for testing a specific computer vision problem. Due to lack of data in the first place, I designed an algorithm which generates new images from the few existing ...