# All Questions

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### R Question: Find a 95% confidence interval for mu

Given that X is a random normal variable with mean=10 and standard deviation=5, generate 500 samples, each of size n = 70, from the distribution of X. For each of the 500 samples, calculate the mean ...
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### Data set distribution by state compared to US pop distribution by state

thanks in advance for your help. -I have a survey data set in which people reported which US State they are from. -I have the proportions of the entire data set comprised of people from each state, ...
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### one-way anova, one group has no variance

I have 20 genotypes for comparison (each has n >or= 5), however one group (control) has no variation (each sample = 100%). Can I apply one-way anova in this case. If not, what test would be better. ...
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### What is shrinkage?

The word shrinkage gets thrown around a lot in certain circles. But what is shrinkage, there does not seem to be a clear definition. If I have a time series (or any collection of observations of some ...
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### Non-Causal time-series filtering techniques for standard noise with unkown variance. (EM vs. weiner vs. kalman)

This is a quick question about filtering stored time-series data using kalman/weiner filtering techniques or expectation maximization. I'm just hoping to fix some confusion about questioning ...
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### Is it invalid to adjust my independent variable based on a regression model fit?

I have a dataset and I want to visualize the relationship between Outcome and Variable1, after adjustment for ...
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### R: Plotting GLM residuals vs. linear predictor or response variable?

When assessing a GLM fit, why is it customary to plot residuals against the linear predictor rather than the response variable? I noticed that plot(glm) defaults to ...
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### Comparison of two measurement methods

all, hope to have your help on one question. For a group of subjects, we have two types of measurements. M1 measured each subject every 6 seconds for 15 minutes, non-invasivly. M2 only measured each ...
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### making predictions with log-log regression model

Is it necessary to exponentiate the predicted values in a log-log regression model? For example my model is: $log(y) = log(x)$ $log(y) = -0.5141 + 0.5377log(x)$ if I wanted to make a prediction ...
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### How to compute empirical copula?

Suppose U is a 4 dimensional data series (x1, x2, x3, x4) each with size n and F(x1), F(x2) and F(x3), F(x4) are marginal distribution functions of (x1, x2, x3, x4). How can we estimate the empirical ...
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### Why does gap statistic for k-means suggest one cluster, even though there are obviously two of them?

I am using K-means to cluster my data and was looking for a way to suggest an "optimal" cluster number. Gap statistics seems to be a common way to find a good cluster number. For some reason it ...
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### Correlation between continuous and binary variables

Is there a way to check for correlation between a continuous variable (year of graduation) and a binary variable (yes/no--took a specific course) with n=85, particularly using SPSS? Our hypothesis is ...
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### Pitfalls in Fitting Nonlinear Models by Transforming to Linearity

Some nonlinear models can be transform to linear models. My understanding is that there might be one-to-one relationship between the estimates of nonlinear model and its linear model form but their ...
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### How may I evaluate my self study of Machine Learning?

I am trying to learn Machine Learning on my own. To do this, I try to read from textbooks, good web-based materials like Stanford or Caltech. I try to work out my exercises, and try to discuss my ...
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### Statistical test for comparing two response options in the same survey item

Is there a way to determine whether the proportion of respondents that endorse one response option of a question is different than the proportion of respondents that endorse another response option of ...
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### Adapting clustering to partial clutering

This is a question primarily about re-appropriating existing clustering methods to work when only a fraction of datapoints are likely to originate from a cluster (as opposed to a global background ...
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### Practical exercise to solve SVM and logistic regression

I have a simple task regarding SVM and logistic regression, even though I know the theory behind SVM and logistic regression I still have a problem to solve them. Exercise. We want to learn a ...
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### What are the differences between filters learned in autoencoder and convolutional neural network?

In CNN, we will learn filters to produce feature map in convolutional layer. In Autoencoder, each layer's single hidden unit can be considered as filter. What the difference between the filters ...
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### Machine learning classifiers

I have been trying to find a good summary for the usage of popular classifiers, kind of like rules of thumb for when to use which classifier. For example, if there are lots of features, if there are ...
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### How to perform a regression with orthogonal polynomials (such as laguerre) in R? [on hold]

Using R software, I'm trying to perform a polynomial regression on E(Y|X1, X2, X3). In fact, E(Y|X1, X2, X3)must ne equal to a linear combination of polynomial with orthogonal basis (such as Laguerre ...
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### Sample size and power calculations for a randomized controlled trial

I need help with the power calculations to determine the sample size of a randomized clinical trial. This is a relatively simple trial with two arms: an intervention arm and a control arm. Patients in ...
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### One-way repeated measures ANOVA vs. two-way ANOVA

In a balanced repeated measures one-way ANOVA, we compare the true averages of a response variable across time points. Are the results about the time effects equivalent to those from a classic two-way ...
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### 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. ...
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### Simulated chi-square distribution doesn't match theoretical

Can someone explain why the distribution of Chi-square values I'm getting (using Pearson goodness-of-fit test) doesn't match the expected Chi-sqaure distribution? The test seems in this case to be ...
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### Loopy Bayesian Networks for bidirectional data flows between nodes?

I have a Bayesian network where the information flows in both directions, i.e. both from parents and children to a specific node. I would like to have both those information flows included and get a ...
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### What makes a good test set in an unbalanced corpus?

So, I have a machine learning classification problem, where the classes are quite unbalanced in the initial annotated dataset. My idea is to use Bootstrap method to help the classifier get new ...
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### What is an intuitive explanation of Echo State Networks?

A reference can be found here: http://www.scholarpedia.org/article/Echo_state_network I am new to Recurrent Neural Networks(RNN) and still learning the concepts. I understand at an abstract level ...
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### Correlation between balance of binary division and modularity in a social network

I'm working with social network data where the full network can be divided up into a ~30 subgroups of nodes based on existing organizational divisions. I'm interested in how integrated each of these ...