# All Questions

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### Auc measure for Local outlier detection in python

I'm using Local outlier factor algorithm provided by Scikit-learn for outlier detection. For the evaluation i want to use auc measure. ...
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### Test Hypothese of a given problem

Hi guys I found this problem in an old book but cant seem to find a solution to it. To be honest I dont really have much of an idea how to go about it. I am trying to study statistics on my own. Can ...
4 views

### Calculate Bayesian point estimator and the Likelihood estimator

Hi guys I found this problem in an old book but cant to find a solution to it. To be honest I dont really have much of an idea how to go about it because I am trying to study statistics on my own. Can ...
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### Interpreting coefficient changes in Cox PH model involving interactions

I read the relevant questions here involving interactions in CoxPH (including 1, 2, 3, 4, 5, 6), and the relevant chapter of Applied Regression Analysis and Generalized Linear Models textbook. However,...
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### How to explain intuitively to a lay audience that the variance is an unbiased estimator?

I have data for the concentration of several chemicals in the milk of 10000 cows and have to explain to policymakers and the lay public (i.e. people with no or limited knowledge of statistics) that ...
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### AR(1) order 0 and coefficients 0 in Sieve-bootstrap Student's t-test for linear trend and Mann--Kendall's trend test

here are my data: ...
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### Scaling different datasets for comparison - Increasing signal 'gain'

I have 4 protein microarray datasets that I am trying to compare. I have concocted a method of aligning them all and comparing them all on a continuous scale which seems to have worked well. These ...
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### How to check if parameters from non-linear curve fits on two datasets are statistically significant?

I have two datasets. They measure a physical response Y (in a certain sample) with increasing concentrations (X) of a certain molecule (dose response). I fit my datasets to a model known as one site ...
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### Can I have a moderator in 2-1-1 multilevel mediation? If so, the moderator should be at Level 1, Level 2 or both? What are the HLM formulas?

Can I have a moderator in 2-1-1 multilevel mediation? If so, the moderator should be at Level 1, Level 2 or both? What are the HLM formulas? To test the interaction effect, can I create the variable ...
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### Statistical term for distribution spanning zero

Is there a statistical word for a data distribution that spans zero? For instance, 'sentiment' data distributions can hypothetically range from negative to positive. The value distributions might be ...
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### How to calculate the Maximum-Likelihood

Hi guys im starting to study statistics on my own and found this problem on a exam paper but cant seem to find the answer of it. Can anyone help me please? Let $X_1, . . . , X_n$ be the random ...
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### How does the Friedman test's average ranks for this data have been calculated?

I have used KEEl tool and another statistical tool to perform the Friedman test. However, these tools returned different results for the average ranks. How does these values have been calculated? The ...
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### R Caret - Random Forest with repeated CV

I am currently struggling to explain the combination of bagging and cross-validation. I am aware of what each does separately but I have difficulties to explain how they are combined (if at all). For ...
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### Is there any valid way to compare two linear mixed effects models based on two different datasets?

I am a Master's student and currently analyzing 2 datasets with reading times as dependent variables. For the first dataset, I used a blocked presentation of the linguistic and visual stimuli, while ...
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### Growth Curve Modeling Using SAS Software Program

The analytical strategy of the study is to define a linear growth curve model for volume measured at three time occasions and also to investigate the influence of therapeutic intervention for a type ...
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### How do we obtain the combined level's HR or OR in a regression model?

I would like to perform a cox PH model. I have identified 4 covariates to investigate the association with survival time. 2 of the covariates are trauma and ...
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### is k-fold cross validation suitable for time series data?

I made a prediction model on time series data using the SVR method then to determine the best parameters I used the gridsearch algorithm and k-fold cv using the R software by default. The data that I ...
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### Linear mixed effect model - heteroskedascity interpretation

I have a dataset with speed difference between men and women on several race distance. The data structure look like this. ...
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### repeated measurements needed for certainty

A bit of a silly question. We have a model, which can be described as y = M(x) + some significant levels of noise. We see that if we repeat the measurements of y N times, we can see a clear ...
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### What is the variance of a constant and set rate?

Say we have two options: 1-out of every 25 videos, one will be promoted 2-every video has a 4% chance of being promoted For the first example, it's meant that after 25 videos, it's guaranteed that ...
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### Computing probability distributions over bootstrap samples for two statistics

I have a data set $x= c(0.9575,0.4950,0.1080,0.9359,0.6326)$ and I'm trying to compute the probability distributions for the statistics $\bar X^* - \bar X$ and $\sqrt n(\bar X^* - \bar X)/s^*$, over ...
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### Differential entropy of a kernel density estimator

I have a set of (~500k) observations that I use to fit a parametric model (univariate three-parameter lognormal). To have an idea of the goodness of fit, I want to compute the Jensen-Shannon distance ...
42 views

### If ε or error rate is normally distributed $N(0, σ^2 )$, why is y also $Y ∼ N(µ, σ^2 )$?

I have the following notes which describe a basic height model: If Y has some distribution with mean µ and variance $σ^2$: E(Y) = µ, Var(Y) = $σ^2$ then this can be written: Y = µ + ε i.e. Data = ...
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### Find conditional expectation given symmetric r.v

How to find $E[sin(X)|cos(X)]$, if X - a symmetric random variable? My attempt: I tried to prove that $sin(X)$ is $\sigma(cos(X))$-measurable. Then it can be argued that $E[sin(X)|cos(X)]=sin(X)$. But ...
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### Simple Linear Regression with Three Level Categorical Variable

Let the following regression equation: $$Y_i = \beta_0 + \beta_1 X_i + \epsilon_i,$$ where $X_i$ is a dummy variable. By setting $X_1$, $X_0$, $Y_1$ and $Y_0$ the variables $X$ and $Y$ when $1$ or $0$ ...
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### Expectation for a function of a discrete random variable

This is a bit on the elementary side, but I'm having trouble understanding if the following formula is a definition, or a derivation. Given that $E[X] = \sum\limits_x xp(x)$, and $g(X)$ is some real-...
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### Why the standard error of the mean never gets to zero even when the sample has the same size as the population?

Why, when we calculate the standard error of the mean for a hypothetical sample with the same size as the population, the value is not equal to zero, if the sample in this case is identical to the ...
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### Intercept of logit vs intercept of multinomial logit

If I simulate the success probability for a Bernoulli random variable $t_{binary}$ conditional on some regressor $x$: ...
19 views

### Show that the weights in IWLS algorithm are always 1

I have a data for fire insurance with a model with the responce variable Y claim size and there are two potential predictor. I have to fit the linear additive model E(log Y_i)=\beta_0+\beta x_{i,grp}...
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### Mode for equal consecutive frequencies

I'd like to calculate the mode for the frequency distribution table: ...
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### Dimension selection based on test accuracy

consider that I have a dataset with train, validation and test set and I want to train the pipeline PCA+logistic regression classifier. So far, for a specific k (that is the reduced data dimension ...
How can you express the average treatment effect on the treated (ATT) in Pearl's do notation? Would it be $E(Y|X=1,do(X)=1)-E(Y|X=1,do(X)=0)$?