# All Questions

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### Random Forest Classification [on hold]

I am trying to make random forest classification but anyway it is doing regression, I can not change it ...
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### the metrics that can be used to characterize and further compare different histogram [on hold]

There is a set of different data set, each of which corresponds to a histogram. Are there any metrics that can be used to characterize the shape of each histogram, and further compare different ...
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### Are same the power of ADF and Hosmer Lemeshow Test? [on hold]

I couldnt understand power of test on statistic exactly.I need examples. If you comment ADF unit root test and Hosmer Lemeshow Test, I will understand.ADF test H0:there is unit root H1:no hosmer ...
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### Time Series assumptions for iid $\epsilon$

thanks for reading my post. I know its fundamental and rather easy qns but I'm seriously struggling. Please help me, thank you very much! Let $\boldsymbol{X}$ have a distribution with mean $\mu$ and ...
17 views

### R: Simulate linear mixed model with matrix algebra

I am trying to learn how to simulate LMM data with matrix linear algebra. So far I've managed to simulate a simple model with a random intercept: ...
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### Time Series Analysis: Determine Which Value Will Be Hit First?

I am analyzing a time series of sales data, and calculating probabilities of certain targets being reached with the assumption that the distribution is normal (Essentially use a ...
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### In linear regression, are the predictors correlated with coefficient estimates?

Consider a gaussian linear model with random regressors $X_i \sim N(\mu_X,\sigma_X^2), 1 \leq i \leq n$, i.i.d. $Y_i | X_i \sim N(\beta_0+\beta_1 X_i,\sigma_\varepsilon^2)$ Are either of the ...
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### difference between RBF kernel ridge and gaussian kernel regression

This may seem a very naif question: theory frameworks behind kernel ridge regression and classic, non-parametric, kernel regression are very different, but still, from a practical point of view, I can'...
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### Odds of pulling same word in card game? [on hold]

A friend and I were playing a card game where you have a hand of letters, trying to make word(s) out of those letters. On the first round we both spelled the same word within only one turn each of ...
10 views

### R: Accuracy Sensitivity/Specificity [on hold]

I want to use Accuracy in a Multiple-Choice Test as my Dependent Variable. I have questions with 6 possible answers, 1 answer is always correct. I have 3 columns: Response, Right Response, Accuracy <...
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### Regression with skewed/half-normal distribution - should I transform, undersample, or something else?

I'm trying to create a regression model using data that are heavily skewed, almost like a half-normal distribution with a mode at zero. The lower scores are over-represented due to sampling technique -...
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### Subjective Prior [on hold]

Let $\theta$ denote the unemployment rate next year. what should be my subjective probability density for $\theta$. Attempt: I know I need to start with a continuous case and then I am kind of ...
43 views

### Can least-squares linear regression ever produce no solution at all?

Is it ever possible for least-squares linear regression (linear in both features and weights) NOT to produce a solution? That is, after we set each partial derivative to zero, can the resulting system ...
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### R-Caret : Not-meaningful class probabilities and AUC value

I am very new to ML therefore my question might be primitive. I am working on a binary-class problem. The response (target) variable is occurrence : a factor ...
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### An easy way to find the PDF of $XY/Z$

Suppose that we know the joint distribution $f_{X,Y,Z}$. I want to find the PDF of $W = XY/Z$ in a way that does not involve too much calculation. I have thought about first finding the Marginalized ...
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### Save frames with detected objects as a video after an object detection model [on hold]

I have a video file (a CCTV footage) which will be fed into a object detection model (YOLO v2 or something faster). I want an output video file that trimmed the portions in which no object was ...
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### Help understanding Vanishing and Exploding Gradients

I am following deeplearning.ai's videos on Coursera. I have a couple of questions regarding vanishing and exploding gradients. The following is Prof Andrew Ngs lecture slides: From what Prof Ng says ...
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### How low should an ICC be to justify disaggregating (i.e. ignore clustering) a multilevel/mixed model?

It is conventional wisdom that ICCs can be used to estimate how much clustering/non-independence is occurring in data consisting of two or more levels. ICCs can inform whether a multilevel/mixed model ...