# All Questions

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### which one is more Efficient estimator on a given data set? [on hold]

I want to know "effiency of estimator" using R or "Relative efficiency of estimators", Here i have 7 co-variance matrix estimators, i want to know which one performed more efficiently then others... ...
38 views

### Which PDF of X leads to a Gumbel distribution of the finite-size average of X?

Consider the statistic "average of $N$ idd random variables $X_i$", $$S_N = \frac{1}{N} \sum_{i=1}^N X_i$$ Consider also that, by a numerical experiment, it is observed that the distribution of ...
14 views

### Interpreting Time series regression/bivariate sorts

I am somewhat unsure how to interpret some result from an analysis that I have done on two independent variables and a dependent variable. My goal is to test whether the abnormal return difference on ...
161 views

### Using time to event data to predict future time to event data

Design: People get drug A and time to an event is measured. Not everyone has the event. Later, most of those people get drug B (those censored and uncensored) and again, time to event is measured. ...
87 views

### How can I estimate the personal parameter (theta) with IRT in R?

I would like to obtain the individual personal ability (theta) estimate under 1PL and 2PL IRT model. I have already the item responses of every participants, how can I do this using the R package? I ...
14 views

### Is HoltWinters() inferior to ets()? [on hold]

here is a simple R program using HoltWinters() function.it gives the following error message even for 100 iterations..(but run smoothly for smaller number of iterations)..But ets() handles the ...
18 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 ...
2 views

### Idiosyncratic error term in fixed effects Poisson

Cameron and Trivedi (2013: 346) and Wooldridge (2010) suggest fixed-effects Poisson with multiplicative heterogeneity.E[y_it│x_it,α_i ]=α_i exp⁡(x_it'β), where α_i is the unobserved heterogeneity. If ...
7 views

### Random Forest Logloss question

I am learning how to use random forest. When I use logloss function to compare my predict model with test data, I got a number greater than 1. Here is my model: ...
82 views

### Age and residual life time of the Poisson process

Original Question Let $N(t)$ be a Poisson process with intensity $\lambda$. Let $T_1<T_2<...$ be the occurrence times. Let $T_0=0$. For any $t>0$, define the $age$ random variable to be ...
158 views

### So survey data cannot be normal distributed?

I am analyzing a data from survey. The data is from a 2X2 between subjects experiment design with 45 subjects in each of the four conditionsThe questions are based on a 5-point or 10-point scale. ...
4 views

### Mean comparison multiple groups

I’m not sure if this question has been asked before as I don’t know how to phrase it in a search. But essentially I’m trying to test if there are differences between store locations that have trained ...
5 views

I'm relatively new to simulations, R, and multiple imputation. I am writing a simulation to better learn multiple imputation on my own. Here is my simulation of MCAR: ...
4 views

### statistical significant deviation cut off point

I have a question with regards to finding a statistical significant difference between two variables. I have 9765 observations of three categories which are "Observed", "Expected" & "Residuals". ...
2 views

### Model name for regression with square root transformation on the response variable

Consider different transformations on the response variable. If log transformation is used: $$\log{Y} = \alpha + \beta X + \epsilon$$ The model is called log-linear model or semi-log model. My ...
2 views

### how to find principal vector and prencipal component from kernel matrix?

i have kernel matrix n*n it as gram matrix how i find U as principal vector as alpha and V as principal component PC by solving eigen value problem as lamda ?how i normalize them ?how i project the ...
35 views

### Is there a formula for an s-shaped curve with domain and range [0,1]

Basically I want to convert similarity measures into weights which are used as predictors. The similarities will be on [0,1], and I will restrict the weights to also be on [0,1]. I'd like a ...
8 views

### Basic RNN not converging to zero

I'm writing a basic RNN in Java using JBLAS. My function for generating the hidden state is: tanh(xU + sW) Where x is the input vector and s is the previous ...
16 views

### Is it possible to train neural network to draw picture in a certain style?

Is it possible to train neural network to draw picture in certain style? (So it takes an image and redraws it in a style it was trained for.) Is there any approved technology for such kind of a ...
203 views

### Automatic feature building/extraction

I have a large time stamped data set (several millions of rows), with known measured inputs xi, where i is a large number to the order of magnitude of 20. The goal is to predict a response yi given ...
219 views

### Distribution of the product of a gamma random variable and a beta random variable

When you multiply a gamma random variable with a beta random variable, you should get a gamma random variable. I'm having a little trouble showing this, though. I figure I'm forgetting some clever ...
25 views

### How to determine seasonality of a binary variable?

I have a dependent binary variable Y, and an independent date variable X. I want to find out if there is any seasonality (at the year level). A few notes: The binary variable is in my model ...
2 views

### Winbugs error Multiple definitions of node V[1,2]

Can anyone see anything immediately wrong with my code that would give this error? ...
7 views

### R , code execution no to stop even after getting error

Need some clarifications for my R code execution stops / terminates after getting error inside while loop but i want my code to run next line which is 2nd while loop and subsequently 3rd loop , The ...
8 views

### Tie in k-nearest-neighbour

I am implementing k-nearest-neighbour classification. I divide the data into 80% training, 20% cross-validation. When a tie happens in cross-validation, should I break it or call this tie a ...
1k views

### Within-group sum of squares of cluster

I have a multivariate dataset for which I have only a table including the cross-wise Euclidean distances between all points and a list giving the assignment of each point to one of several clusters. ...
2 views

### Identifying sequential patterns and deciding which ones are useful

So, basically I have a problem in which I have, over time, the appearance of different features, each feature containing different categories (where categories belonging to the same feature cannot ...
6 views

### how to classify short text sentences?

I have a very large dataset that looks like ...
7 views

### SVD a practical approach question

This might be a very stupid question, but I have read the great comments regarding how to deal with missing values before applying svd, but I would like to know how it is going to work, if I apply it ...
6 views

### How to solve eigen value problem in kernel pca?

If I have kernel matrix $K_{n*n}$, where $\alpha$ is an eigen vector, and $\lambda$ is an eigen value, how can I solve the eigen value problem to find principal vector and principal component?