# All Questions

134,595 questions
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### Selection criteria for penalty parameters in the ridge multinomial logit model

I appeal to you for the following doubt. I am adjusting a ridge multinomial logit model but I have problems in the criterion when choosing the lambda parameter that gives better results, besides ...
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### How to show that cov(Yi, Y-bar)= (σ(^2) y)/n

I'm trying to figure out how to do this proof, and then use it to show that sample variance is an unbiased estimator.
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### Visualizing separability / independence

I’d like to visually ‘see’ the independence of random variables. I tried plotting f(x), f(y), and f(x, y) for independent and dependent pairs of variables. However, the difference is still not ...
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### Advice on ML ideas/models for a data set I have

I have a very large marketing data set (300GB in size) and I am wondering what ML models I can apply to it. The dataset consists of transactional data from supermarkets. The type of data I have is the ...
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### Correlation above 1 between second-order and first-order latent variable

So I ran CFA on an exhaustion measure comprising of three facets which were specified as first-order latent variables. When I added a secon-order latent variable to the model the correlation between ...
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### Data exploration to determine if GAMs are appropriate

How to decide, based on data exploration, between a GAM and a GLM. Linear Models (LM) assume that the relationship between the response and the predictor are linear. Generalized Linear Models (GLM) ...
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### How to conduct power analysis for unbalanced one-way ANOVA in R?

I am looking for a way to conduct power analysis for unbalanced one-way ANOVA in R. I found the pwd package; however, it only allows me to calculate power for ...
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### Estimating Differential entropy from unbiased samples of a probability distribution

If I can get N unbiased samples $x$ from $p(x)$ how can I approximate the Differential entropy: $$H(X) = -\displaystyle\int_{x} p(x)\log p(x) dx$$ I'm not very knowledgeable in statistics so I'm not ...
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### I am facing the same error [on hold]

mydata3=mydata2[,c(2,4,7,9)] set.seed(123) model <- train(fwd_def_status ~., method = "rpart" , data=mydata3) What to do in the case where my dependent var is part of mydata3?
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### forget_bias interpretation in tensorflow

In Basic LSTM cell of tensorflow there is an argument named forget_bias. From the documentation of ...
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I have a question concerning unit-root data and normal distribution. As an assignment, I am checking the long-term relationship between unemployment rates and labor force participation rate. First I ...
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### Weighted covariance with different reliability weights?

Suppose observables $X$ and $Y$ possess different reliability weights $w_{x,i}$ and $w_{y,i}$ for the possible elements $x_i\in X$ and $y_i\in Y$ respectively. Considering a sequence of consecutive ...
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### Out-of bag error in Random Forest

I am trying to code my own, simple version od RandomForest function in R for learning purposes. However I have a hard time understanding the concept of the out-of-bag error. Is it simply done by ...
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### Is it reasonable to display “percentage data” in a boxplot, why?

I have data that are in fact percentages of C (bound to clay) combusted in a certain temperature interval. Exemplary data: ...
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### What test for a 4-level categorical variable and a continuous variable?

I'm currently doing research on whether image quality affect engagement. Image quality is given in 4 categories (bad, benchmark, semi-professional and commercial level) and engagement is in how many ...
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### Asymptotically unbiased estimator vs consistent estimator

I'm wondering if there is a difference between an asymptotically unbiased estimator and a consistent estimator. For asymptotically unbiased estimators, the expected value of the estimator converges ...
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### how to use Likert Scale to prove hypothesis

How to use data collected from likert scale (five point) to prove hypothesis. For example. Hypothesis 1: Internet marketing is cost efficient. Statement 1: internet marketing required less budget. ...
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### Use PCA in order to show impact of variables on clusters

I did a clustering of selected variables. Is it possible to use the PCA (contribution, correlation) in order to show the impact of each variable in the clustering? (cfr. image 1) and add complementary ...
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### GWAS genotype/phenotype datasets for supervised learning model testing

I'd like to play around with several ML models and test their predictive power using some good datasets. I need datasets of genotype (a set of SNPs) and phenotype (some trait). If possible, I'd ...
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### How many parameters are in this specific model

I am planning on doing Structural Equation modeling on the following model that is pictured: I am trying to calculate my needed sample size. I have read the rule of thumb is 200 for SEM or 20 cases ...
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### Do these standardized residuals show heteroskedasticity?

I'm practising in the individuation of heteroskedasticity from the standardized residuals. I know that, if the time series is homoskedastic, the spread of the residuals should be constant and random ...
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### What type of R-squared measure should I use? [on hold]

There are several R-squared types out there for generalized linear models. As far as I know, the choice of R-squared depends on the error distribution assumed and the link function used. So my ...
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### glmer model convergence question

We are working with a longitudinal dataset, with three variables: WAIP, BPSRRI and group. WAIP and BPSRRI are measured repeatedly for 10 times and group refers to the group assignment of our subjects ...
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### What does it mean by “approach the performance of the Bayesian gold standard”?

It is a sentence in Dropout paper(Dropout: A Simple Way to Prevent Neural Networks from Overfitting). "This can sometimes be approximated quite well for simple or small models, but we would like to ...
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### Must all supervised algorithms have (complexity) parameters?

I have noticed that all commonly used supervised algorithms (decision tree, logistic regression, random forest, ...) have some (hyper)parameters to tune (otherwise the model may underfit or overfit ...

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