# All Questions

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### Prediction Interval for Loess Forecast

I have consulted this question on the basis of prediction intervals for loess (How to calculate prediction intervals for LOESS?). However, I am unaware of whether it is proper or possible to use ...
6 views

### Modeling an indicator variable with continuous properties [on hold]

I'm trying to model auction participation for a single individual. It occurs to me that their participation is binary (yes/no), but also continuous in the 'yes' case. Any general pointers for how to ...
2 views

### Canonical Analysis on experimental design software

Does Design Expert 8 performs Canonical Analysis? I am doing research for my masters degree. I am applying Response Surface Methodology (RSM) that uses a d-optimal designed experiment to optimize a ...
2k views

### 40,000 neuroscience papers on fMRI might be wrong

I saw this article in the Economist about a seemingly-devastating paper [1] casting doubt on "something like 40,000 published [fMRI] studies." The error, they say, is because of "erroneous statistical ...
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### Normalization/Standarization for Clustering visualization

I'm performing visualization of a dataset clustered with k-means. I compute a weight for each cluster and I draw a circle as big as its weight. But it seems like after the clustering some values are ...
19 views

### Help in unsupervised problem formuation for parameter estimation

In the supervised learning problem, the goal is, given a training set, to learn a function $h : X \mapsto Y$ so that $h (x)$ is a “good” predictor for the corresponding value of $y$. If $y$ takes ...
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### When is LHS sampling a good idea?

In this paper: http://salserver.org.aalto.fi/vanhat_sivut/Opinnot/Mat-2.4108/pdf-files/emat08.pdf equation 6 shows that if $cov(f(x_1),f(x_2))$ is positive LHS does not reduce random sampling error. ...
395 views

### Analyzing relationships between ordinal and continuous time series data

I have two sets of time series data - roleTrajectories & normalizedDegree. The former data set contains ordinal rankings of subjects' positions within a network at 13 time periods. The latter data ...
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### RNN - What are timesteps?

I am completely new to the recurrent neural network models. I am using rnnlib to run their examples. What is the meaning of timesteps in the output ? Do timesteps mean that number of output the RNN ...
4 views

### Levels of a categorical variable in Wilkinson-Rogers notation without intercept

I would like some clarification regarding a regression specified using Wilkinson-Rogers notation to produce coefficients for all levels in a categorical variable. Consider the regression specifed by <...
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### Questionnaire Analysis Resources

Looking for resources (online resource, book, etc) that details how to analyze questionnaire data. I would like the resource to specifically deal with multiple choice questions, differences in sample ...
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I'm working through Convolutional Neural Network paper here on adversarial learning and I'm having trouble with the derivative proof of adversarial logistic regression. The correct answer presented (...
5k views

### Probability of a single real-life future event: What does it mean when they say that “Hillary has a 75% chance of winning”?

As the election is a one time event, it is not an experiment that can be repeated. So exactly what does the statement "Hillary has a 75% chance of winning" technically mean? I am seeking a ...
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### Method for quantifying intervention effect in time series

How can the magnitude of an intervention be quantified in a segmented time series regression? I am attempting to replicate the methodology of Decline in pneumonia admissions after routine childhood ...
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### A measure of “variance” from the covariance matrix?

If the data is 1d, the variance shows the extent to which the data points are different from each other. If the data is multi-dimensional, we'll get a covariance matrix. Is there a measure that gives ...
6 views

### A strange finding with the logrank test statistics

When I try to confirm the type I error rate of the logrank test by simulation, I found something strange... Firstly, I generated 100 observations from exponential distribution with lamda1=1 as group 1 ...
164 views

### Does word2vec have context between sentences?

The word2vec system wants each sentence on a line by itself. Does the context continue from one sentence to the next in the input file. That is, does the first word in a sentence get context from ...
50 views

### 3-way interaction Stata [on hold]

I have a panel data in the following form: <id> <city> <treated> <time> <after> where id identifies the individuals in my panel, ...
40 views

### Continuous process vs Discrete process!

I encountered two statements in Tibshirani's article Regression Shrinkage and Selection via the Lasso, p.58 (pdf). Subset selection is a "discrete process" which leads to unstable coefficients. ...
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### Is an SLA pulled by just the calls answered by a certain group and not for the whole Queue valid?

I am trying to determine if the following is a valid SLA, I was presented with this as a fix for us not being able to differentiate the SLA between multiple groups answering calls: 1 Queue Two ...
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### Soft Question - Practical Statistcs: What to learn, why learn it and how? [on hold]

BEGINNING: I want to ask a few soft questions about statistics. I understand that maybe/probably some/all off these questions cannot be answered categorically but I would like to try and get some ...
917 views

### How do we know that the probability of rolling 1 and 2 is 1/18?

Since my first probability class I have been wondering about the following. Calculating probabilities is usually introduced via the ratio of the "favored events" to the total possible events. In the ...
1k views

### C5.0 Node Decision Tree with Boosting Algorithm (SPSS Modeler)

We are currently looking to mimic the SPSS Modeler's C5.0 Node decision tree model with boosting, which means we'd like to rewrite the whole thing in plain Java. I ...
29 views

### Jointly Complete Sufficient Statistics: Uniform(a, b)

Let $\mathbf{X}=x_1, x_2, \dots x_n$ be a random sample from the uniform distribution on $(a,b)$, where $a < b$. Let $Y_1$ and $Y_n$ be the largest and smallest order statistics. Show that the ...
188 views

### What books to read for MCMC theory?

Suppose one is interested in stochastic processes for the purpose getting a theoretical understanding of MCMC. They already have a decent understanding of probability theory (let's say at the level ...
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### Build funnel plot (not chart) in Excel or/and SigmaPlot or/and SPSS

Could someone please advise me how to build a funnel plot in excel (SPSS could also work, however I am 99% sure it cannot build such charts) or SigmaPlot. I need it to look EXACTLY as in the attached ...
47 views

### How can I assess variable importance for each individual observation?

So most regression models and data mining technique have ways to assess the importance of each variable in explaining the response. This is great, but how can I assess variable importance for each ...
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### Testing simple slopes in multilevel modeling

I am currently working on a project where my coworker and I are examining the relationship between different aspects of friendship quality and achievement across three time points (grades 3, 5, and 6)....
101 views

### seasonality detection

I'd like to detect seasonality in my timeseries which consist of daily observation 96 per day,one for every 15 min, for a duration of 3 months. In the acf plot, I see a consistent 3 spikes, does ...
18k views

### Interpreting interaction terms in logit regression with categorical variables

I have data from a survey experiment in which respondents were randomly assigned to one of four groups: ...
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### Prediction of next event occurrence

I am working on a request prediction problem in which I have to predict which object will be requested in the near future and how many times. This is like a basic internet traffic request pattern on a ...
212 views

### Implementing chi-square in python and testing on scipy's poisson and norm variates

I need to implement Pearson's chi-squared test to test random variates. But I get very different results using different sequence length,degrees of freedom or even seeds. Only a few times sequences ...
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### Compare models with different number of observations (data with strong gender bias )

I am analyzing gene expression data (RNASeq) from patients with recessive X-linked mendelian disorder. What it means is that all affected individuals are males, but controls are both males and females....
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### What is the difference between Vector Auto regressive, Dynamic Regressive, and ARMAX models?

All of these models seem to be used in predicting an endogenous time series variable, using several lagged exogenous time series variables. If it is so, how do we decide when to use which. Thanks.
3k views

### Why do we divide by the standard deviation and not some other standardizing factor before doing PCA?

I was reading the following justification (from cs229 course notes) on why we divide the raw data by its standard deviate: even though I understand what the explanation is saying, it is not clear ...
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When I run ...
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### Weighting aggregated survey data at the subnational level

Goal I would like to figure out how to weight aggregated survey data to try to 'fix' the fact that a survey is not representative at the subnational level. Background I am attempting to aggregate ...
11 views

### Using multiple ranked lists to achieve a single rank

I have a feeling this may yield a simple answer, but as I am not very mathematically inclined, I'm afraid I am uncertain how to approach this. I have 4 different ranked questions as follows: What ...
406 views

### Tradeoff batch size vs. number of iterations to train a neural network

When training a neural network, what difference does it make to set: batch size to $a$ and number of iterations to $b$ vs. batch size to $c$ and number of iterations to $d$ where $ab = cd$? To ...
15 views

### Random effects negative binomial model in Stata

I am running a random effects negative binomial model for count data. Patients were randomized to 3 treatment groups and were seen over varying number of visits (time) i.e. the data is not balanced. ...
10 views

### p-value for non normalized data [on hold]

I'm working on a project where I want to apply the output of a neural network in conjunction with a greedy (prediction) algorithm. The project is segmentation of 3D volumes. The greedy algorithm ...
17 views

### Interaction between 2 quadratic variables

If I have a regression y ~ x1^2 + x1 + x2^2 + x2 + bias, and I want to include interaction between the two quadratic variables, do I make the new regression y ~ x1^2 + x1 + x2^2 + x2 + x1^2*x2^2 + x1^...
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### Tune parameters from a specific equation in R

This is the first time I am truing to tune model parameters in R. I have a fairly complicated equation with multiple parameters: ...
30 views

### Ensembles - few questions on approach with multiple models

I'm looking for some general-high level understanding of how I should apply ensemble techniques. I understand that some models can be already thought of as ensembles - such as random forests or some ...
11 views

### Training classification/clustering with regression data

I have a problem with continuous feature and outcome data. The features are weak predictors. I'd like to be able to cluster my features into $k$ classes. This is not semi-supervised learning so much ...
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### Why does the CV estimate of Test Error Underestimate Actual Test Error?

It is my understanding that the k-fold cross-validation estimate of test error usually underestimates actual test error. I’m confused why this is the case. I see why the training error is usually ...
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### Pairwise comparisons between GLMs

Apologize for the novice question up front. I'm curious if there's a way to compare glms in R. I've seen some posts on ANOVA, however my independent variable is not categorical, so I don't think it ...
459 views

### How to compare forecasting methods?

I have several intermittent data. Based on those data, I would like to compare several forecasting methods (Exponential Smoothing, Moving Average, Croston, and Syntetos-Boylan), and decide whether ...