# All Questions

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### Non-independent variables (covariates) in survival analysis

I want to perform survival analysis, and compare at which of 3 spatial scales habitat variables affect the most nest survival. I thought to perform analysis separately for each spatial scale and ...
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### Interesting Logistic Regression Idea - Problem: Data not currently in 0/1 form. Any solutions?

I am attempting to conduct a logistic regression for a tennis analytics project, endeavoring to predict the probability of a player winning a point in which he is the server. My response variable ...
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### Min and max range from standard deviation

If I have 2 data points like 16.70 (+/-4.33) 54.70 (+/-16.30) where 16.7 = mean and +/- 4.33 is the standard deviation, is it possible to calculate a range out ...
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### How can compare a Poisson model against a Quasipoisson model in GAM?

I have count data of species and I would like to fit a GAM model in mgcv with poisson distribution. The poisson model has overdispersion so I have read that is better to fit a quasipoisson ...
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### Where is the original data set for the “German tank problem”? [migrated]

I am looking for the original data set for: the "https://en.wikipedia.org/wiki/German_tank_problem" , but can't seem to find it. Any suggestions on where it might be available from? Thanks.
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### When is the conditional differential entropy maximized?

Let $Z_1$ & $Z_2$ be 2 i.i.d. RVs, each distributed according to $N(0,1)$, and let $X$ be an arbitrary RV with zero mean and unit variance. What distribution of X will maximize this conditional ...
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### what does the scale within a PCA mean

I am searching for an explanation what the x and y axis within a PCA analysis really means? I could not find any explanation on this topic, can somebody help me with it? So, just as an example ...
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### Is SVM still an active research area?

Recently I am learning SVM classification and regression, I found that most of the work are proposed in the 2000s, (around 2004~2007), but I don't understand why people stop developing it(do they?), ...
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### When removing outlier is right? Removing techniques for outliers in R [duplicate]

I was searching outlier removal in R and I saw some comments related to almost never you should remove outlier from dataset. I wonder when we should remove outlier? I have a dataset consisting ...
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### Ordinal Dependent Variable and Ordinal Independent Variable. Which test to perform analysis with?

I have a question regarding Ordinal data. I have measured 'Attitude towards a product' using Likert scale and I have measured 'Purchase Intentions to buy the product' also using Likert scale. Now I ...
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### Logistic regression: Include a specific time variable to account for unexplained changes over time?

I am measuring the effect of specific marketing activities on the likelihood to buy a product. The Marketing activities start on a specifc date. All the products sold before this date a marked with a ...
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### Relationship of instantaneous variance and VIX with conditional density functions

I read a paper about the VIX which contains a stochastic volatility model. To estimate the parameters of SV (to be later able to price VIX futures), they derived a conditional probability density ...
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### Does correlation implies mutual information?

I am skeptical about the notion that if mutual information between two random variables is non-zero (existence) this doesn't imply the existence of correlation between them BUT existence of ...
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### Multiple regression - High adjusted R^2 but the residuals are high

I used the multiple regression models to derive the outcomes after using AIC pairwise comparison and deleted the outliers, high leverage points. And it seems good, the adjusted R^2 acheived 0.9543, ...
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### Removing outliers based on cook's distance in R Language

I have this R code for linear regression: fit <- lm(target ~ age+sales+income, data = new) How to identify influential observations based upon cook's distance ...
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### Logistic regression in R, basing on which class(0 or 1) in dependent variable the modelling is performed

In R and in binomial logistic regression to be specific, the modelling is based on which class amongst 0 and 1? And if it builds model based on 1 by default, is there a parameter or something in which ...
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### Categorical explanatory variables in Poisson regression

I want to perform a Poisson regression to explain Abundance (Counts of individuals) through a number of continuous and categorical explanatory variables. Some of the categorical variables have more ...
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### Analysing pattern in data

I am pretty new to analytics and I have a data received from sensor about the water usage .The readings are taken at 10 sec interval.I would like to know what kind of analytics methods can be applied ...
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### Logistic regression in R, basing on which class(0 or 1) in dependent variable the modelling is performed [on hold]

In R and in binomial logistic regression to be specific, is the modelling done based on which class amongst 0 and 1? And if it builds model based on 1 by default then is there a parameter or something ...
29 views

### Data Analysis in psychiatric

A 30 item questionnaire in accept or decline form consisting of commonly encountered dysfunctional beliefs about psychiatric issues was administered to medical students. The questionnaire is in the ...
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### Curve registration for plots with significant fluctuations [on hold]

I am doing some stuff about functional data analysis, but I come across some trouble when I try to analyze curves with significant fluctuations. I use the sample data "StatSciChinese" in "fda" ...
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### Is it valid to rank goodness-of-fit based on the value of the Kolmogorov-Smirnov or Anderson-Darling test statistics?

When using Kolmogorov-Smirnov or Anderson-Darling goodness-of-fit tests, is it valid to claim that, because distribution X has a lower test statistic than distribution Y, distribution X is a better ...
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### why bootstrap result in overfitting for randomForest prediction?

I am dealing with an imbalanced dataset with the R package randomForest. Some one has suggested that, Bootstrap your data while over-sampling the rare class and under-sampling the typical class. But I ...
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### R Matrix correlation non-numeric

Dear More Advanced that I R users, I am having a problem creating and interpreting some data. Here we go with the question and please let me know which parts are not clear. I have some data that I ...
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### reshape data with repeated and alternating column names [on hold]

I am a beginner with R, and I would like if someone can walk me through this issue. I have a data set with three variable x, y, z and many rows. The variables repeat every year in columns for 45 ...
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### Possible to estimate distribution around mean given #samples, mean, highest and lowest?

For a project for which there are multiple bidders, the following is known: Number of bidders: 24 Mean bid: 104 Highest bid: 356 Lowest bid: 20 Given the above, is it possible (however roughly) ...
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### How does the R function arima() calculate its residuals?

I am new to time series and I am trying to figure out exactly what does on beyond the scenes in R. Say I have the MA process: $$y_t - \mu = a_t+\theta_1 a_{t-1} + \theta_2 a_{t-2}$$ where $a_t$ are ...
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### RStudio RMarkdown PDF generation has bug / flaw with R Projects [on hold]

This is something that had confused me for a while. I figured it out, then ran into the same problem again, so I wanted to be sure to post it to help out others. As RStudio has become more robust ...
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### Python/R Exploratory Data Analysis for Classification

Are there preexisting functions in Python/R that create exploratory data analysis plots like the following:
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### Does RBF-network (~Nadaraya-Watson kernel smoothing) work in high dimensions?

It seems that a single-layer RBF-network with normalized weights is the same thing as kernel smoothing (see e.g. Haykin "Neural networks: a comprehensive foundation", Section 5.12). Then - it's ...
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### How to mathematically prove that the continuous data is better for finding out the correlations than the binary data? [on hold]

If I want to calculate the correlations among the components in a vector space using the MLE with a prior of multivariate Normal distribution, which kind of data should be better? The binary data or ...
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### Q-Test of Heterogeneity for only two effect sizes?

I am using the Q-Test of Heterogeneity to investigate if several effect sizes derived from two different studies are significantly different from each other. More precisely, I have, for every effect ...
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### On estimating ARIMA models on artificially made time series data

For each day, I observe my variable, y(t), for a period of 12 hours. In order to understand the data and make predictions, I want to put together these data and ...
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### Fixed Effects vs Lagged DV vs. First Differences Regression

What are the differences between using unit fixed effects, unit fixed effects and time fixed effects, lagged DV, or first differences to analyze a time series with 4-5 time periods and 35-50 units per ...
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### How to find the threshold that maximizes the F1 score?

I have a probabilistic, binary classifier. Is there any principled way to select the threshold that maximizes the F1 score? Currently I simply choose many different thresholds, apply them on some ...
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### Multiple categorical and continuous variables in ANCOVA

I have performed an experiment where insects in a certain order were captured and identified at set distances from a forest boundary. At each point I have measured a number of environmental variables ...
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### Method for correlating ordinal and continuous data

I have data from several dozen forest inventory plots. Tree canopy cover of each plot was assessed in the field and placed into one of 5 categories (analogous to very high, high, medium, low, none). ...
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### Application of Zivot-Andrews and Clemente, Montañés, Reyes unit root tests throws error [migrated]

I am trying to run the zandrews and clemao / clemio commands in ...
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### How do one interpret the results of wilcoxon-mann-whitney test in SAS?

I have done the Wilcoxon test in SAS. My class variable is race. I got a low p-value. What exactly does that mean?
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### Is there a typo in this paper on Slow feature analysis?

In this picture you can see the formula (red rectangle added by me for emphasis): $$\textbf{V}^\intercal\textbf{HV} = \textbf{D}$$ Should not this rather be (eigenvalue decomposition):  ...
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### Difference between scipy pairwise distance and X.X+Y.Y - X.Y^t [migrated]

Let's imagine we have data as ...
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### R lsmeans in a model with two residuals (split-plot) [on hold]

Let's assume the model: lm(VAR ~ A * B + (A : R), data) which produces this ANOVA: ...
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### Can Random Forest be used for Feature Selection in Multiple Linear Regression? [on hold]

Since RF can handle non-linearity but can't provide coefficients, would it be wise to use Random Forest to gather the most important Features and then plug those features into a Multiple Linear ...
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### How to precompute foldid with even observations per fold for glmnet [migrated]

According to the glmnet vignette, a foldid can be set up by: foldid=sample(1:10,size=length(y),replace=TRUE) However, if you ...
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### WEKA accuracy confidence interval

I have a dataset consisting of thousands of companies from the UK. For 300 of these companies, I collected several indicators which were extracted from social media (e.g. #likes). I have built a model ...
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### Setting different depth in rpart, but didn't actually change

I am tuning my decision tree with different depths. I wanted to see my results for trees with depth from 6 to 12. Instead of creating a loop, I am manually changing the parameter. My problem is, ...
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### Slice sampler in PyMC gives values outside support of prior

When sampling variables with Uniform or Beta priors in PyMC I'm getting some very strange behavior. The sampler ends up drawing values far, far outside of the support of the prior. Here's a simple ...