# All Questions

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### Plot large high dimensional dataset

I have a high dimensional dataset (12 variables) with 42000 observations. I made a clustering and i have evidence to choose five cluster.So i want to plot with some tools my dataset to show (if it is ...
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### Problem Calculating Standard Error

I have a set of individuals categorized into two classes as follows: ...
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### MCC or F-measure, which measure is the best to represent multi-class confusion matrix

I'm building a classifier of multi-class problem. In my context I have to classify vehicles into five categories: cars, vans, trucks, buses and motorcycles. I would like to use some measure to ...
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### type 1 and type 2 errors for non-normal residuals in a regression

He guys, I did a regression and performed normality tests on my residuals, which reject the NH that the residuals are normally distributed (the true distribution seems to be flatter with fatter ...
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### How to select weights in the F-Measure to be aligned with that used in cost-sensitive SVM training?

I am dealing with a classification problem in which Recall is more important than Precision, and the training dataset is an imbalanced one. The approach I am taking is to use oversampling to mitigate ...
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### Using contrasts in Poisson regression

I don't really understand how to use contrasts in regression analysis. We have devided the participants in our sample into 6 groups, according to their body mass index at baseline (3-class variable: ...
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### Sequence of probabilities

The probability distribution of a random variable X is $P(X=k)=p_k,k=0,1,2,...$ and $\frac{p_k}{p_{k-1}}=a+\frac{b}{k}$. If $p_0=\frac{1}{9},p_1=p_2=\frac{4}{27}$,what can be said about the sequence ...
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### Linear regression (best fit line) on moving averages vs raw data?

I have a series of sets of data over a period of time, with the amount of data available being quite variable between sets. One has points for almost every day but is really quite noisy; another has ...
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### Unbiased estimator of poisson parameter

The number of accidents per day is a Poisson random variable with parameter $\lambda$, on 10 randomly chosen days the number of accidents were observed as 1,0,1,1,2,0,2,0,0,1, what will be an unbiased ...
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### What is the difference between GAS ( Generalized Autoregressive Score) model and a GARCH?

I am trying to analyze some data about Brent Oil volatility. So far I have managed to fit a GARCH(1,1) model and an EGARCH. However, someone has recommended to use a GAS model, Generalized ...
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### Use case for Anomaly Detection using the multivariate gaussian distribution

Given the following real world problem: We have 5000 vehicles of DIFFERENT models (trucks, small cars, large cars) with 100sensors in each car (measuring consumption, distance, averange speed etc for ...
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### Consultancy or research scientist in medicine/bioinformatics in West Europe

I'm a mathematician who's working as a postdoc on statistical modeling of biomedical data, combining statistics and differential geometry. I'm not well familiar with machine learning (ML), but gaining ...
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### Conflicting intuitions re linear systems in levels vs shares

Suppose I have a set of components that sum to some total value, different in each period. Call the total Y. I have a set of equations, linear in the (sometimes transformed) variables, each ...
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### Can I add categorical variables in NARX

Can I add categorical variables as exogenous variables on NARX(in Matlab)? Eg: Type of day, Month
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### Is it possible to derive a relation between parameters in Poisson process representation of extremes and parameters in GPD model?

I want to derive the theoretical relation between the parameters in a point process model for extremes and the parameters in the GPD model for extremes. I'm following Coles - An introduction to ...
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### Hourly electricity demand data finding AR and MA terms

I am new to time series analysis. I have hourly electricity demand data for five years (having multiple seasonalities as daily,weekly,annually) and I want to guess the number of AR and MA terms using ...
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### Neural Networks to Explain User Behavior

In the past I've used logistic regression to not only predict user behavior, but to understand the relative importance of each variable to help the business teams understand which levers they can pull ...
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### Unbiased estimator of binomial parameter

Let 4,3,5,2,6 are 5 observations of the binomial(10,p) random variable.What will be an unbiased estimate of $(1+p)^{10}$ ? I have tried to solve the problem in this way. We know that ...
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### Can PCA be applied to normalized features?

I want to perform feature dimension reduction using PCA. The feature is 256 bin normalized histogram of images. I would like to reduce feature dimension to less than 256. I centered the train and test ...
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### a hypothesis test for evidence that one thing is dependant on another

I'm not sure what the null hypothesis for this would be/ what the correct symbols are. the data is unpaired and I'm needing to find if there evidence ( at 5% level of significance) that one thing is ...
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### Measuring the effect of weather on retail sales

I'm currently working on modeling this as an ad hoc. Sr mgmt want to know how much of our sales growth during the year can be attributed to weather. I chose to investigate "weather" as temp & ...
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### How to calculate mean average precision given precision and recall for each class?

I use Pascal VOCdevkit to calculate object detection average precision for each class, but how can I get mean average precision for the whole dataset? Should I average each average precision or should ...
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### How do we obtain E(exp(C+By-Y'aY))?

How can I prove this ? I did get $B-2uA$ by identifying the $a+by+cy^2= -1/2 (y-u)^2/\sigma^2$ But, I don't know how to get $(2a+\Sigma^{-1})^{-1} \dots$ Am I missing something? A little help would ...
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### hypothesis testing for two sample

I have two samples and I need to do hypothesis testing to see if the mean has changes between these samples and I don't know what data I should use as I have 2 SE mean and standard deviation one for ...
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### Estimation of causal effect in experiments with lots of missing values

This is a generic question. Suppose you run an experiment with units randomized between a treatment and a control group. Imagine the response rate is very low in each group, say, below 10% and with a ...
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### Any way to make density estimate from the data with importance factors? [on hold]

I have a data with probabilities: $<x_i,p_i>$ which can be used to approximate CDF (build stepwise function and then smooth it). How can I get smooth density estimate from this data in R? All ...
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### How to mitigate risks for an oversampled training and validation set for a Zero-Inflated Poisson model?

I have a data set, with training, validation, and test already decided for me. It is a mailing list response project so it has a lot of zeroes representing no response, and some ones representing a ...
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### What is a hard data set for support vector machines?

Suppose that: There are only numeric features in the data set. There is a binary target variable (since a general nominal case is resolved by 1vs1 or 1vsTheOthers approaches). I have noticed that ...
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### Formulate equation after fitting to log(y)~x) using lm() [duplicate]

Following code was used to fit a function to my data; ...
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### Adding a glm regression to a ggplot, where datapoints are colored after groups [migrated]

I am trying to visualize a regression by adding it to the data plot, but I want to color the data points after group (eight different groups) and then ggplot makes a glm line each group instead of one ...
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### Difference in Beta random variables

I am having trouble deriving the distribution of the difference of two beta random variables and would like some help verifying the steps I have taken. In particular calculating the bounds. Say I ...