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8 views

Auto.arima application in R with sub-daily data - No seasonality given [duplicate]

I'm working on a R code and my aim is to make forecasts with a model chosen by applying auto.arima function on my data. These are recorded every 6 minutes, so we're dealing with sub-daily data. ...
4
votes
1answer
56 views

What is the expected distance to the nearest molecule?

You may assume any easy model without collisions/attractions, molecule diameters of 0 and perfect mixing. If you have 500 copies per micro-m^3 of molecule A , then each molecule A has a box of 125 nm ...
1
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0answers
11 views

Bayes Factor Analysis

I am new to Bayesian statistics. I have one group (n=10) with two measurements per subject (before/after a treatment manipulation, i.e., Phase "2" and "3" below). I originally used ...
0
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0answers
9 views

What is the correct procedure for building time series models?

This is a question about the correct procedure for building time series models. For most (non-time series) supervised machine learning problems, the advice seems to be to build models by: ­using a ...
1
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0answers
9 views

What is this measure of error called?

I am investigating prediction errors in a context where the errors can be extremely large. Someone advised me that in addition to reporting the mean or median of the absolute errors $$|\hat{x} - x|$$ ...
-1
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0answers
7 views

Should I be worried about rank deficiency? [duplicate]

I am trying to do a mini project using a dataset sourced from online sources. It has 400+ observations with 8 variables. ...
0
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0answers
6 views

Theoretical Results Regarding the Sum of OLS Coefficients

Consider the following regression model $$ y=\beta _{1}x_{1}+\beta _{2}x_{2}+u $$ where $x_{1}$ and $x_{2}$ are two random variables and $u$ is a disturbance term. I simulate the model drawing $x_{1}$,...
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0answers
5 views

Avg. treatment effect

I am a bit confused between calculating the treatment effect per category and the average treatment effect in the whole sample given the following table: $$\begin{array}{l|cc|cc} \hline \hline \text {...
0
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0answers
8 views

CART ALGORITHM : Machine Learning [closed]

I tried to solve this but couldn't understand the problem? Help Q) Try to manually compute the first split point that the CART algorithm would do on the following dataset, use x as feature. x: 1 2 7.0 ...
3
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0answers
10 views

Estimating a linear system of simultaneous equations at once

Consider the following simultaneous system $$ y_{1} =\beta _{1}y_{2}+\alpha _{1}z+u_{1} \\ y_{2} =\beta _{2}y_{1}+\alpha _{2}z+u_{2} $$ where $y_{1}$, $y_{2}$ and $z$ are random variables each of ...
1
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0answers
16 views

For binary classification learning problems, how should I label instances where I'm only 60% sure?

I've come across a few binary classification problems lately where the labelling was challenging even for an expert. I'm wondering what I should do with this. Here are some of my suggestions to get ...
0
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1answer
14 views

Cumulative distribution function equals almost surely

Let $F_1, F_2$ - two continuous CDF. if $F_1 = F_2\quad F_2$ almost surely (i.e. probability of $x$ where $F_1(x)\neq F_2(x)$ is zero with respect to probability with CDF $F_2$). Then $F_1 = F_2$ (...
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0answers
13 views

IRLS for LASSO problem

I'm trying to solve the following (here simplified) problem (here 1D, and $x>0$): $$ \arg \min_{x} \frac{1}{2} \left\| A x - b \right\|_{2}^{2} + \frac{1}{2} \left\| x \right\|_{1}$$ I need to ...
0
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0answers
5 views

Contingency table - can I build this contingency table directly in R? [closed]

I am really getting started with R, so I suspect that this is actually an easy problem, and I am just a Newby that couldn't solve it. I need to build a contingency table where I can see how ...
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0answers
4 views

interpreting lavaan output and model

My question is similar to a prior post, but differs in that I am trying to do path analysis through lavaan and my output is different. See :How do I interpret lavaan output? Essentially, my model is ...
0
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0answers
4 views

Goodness of fit for heavyLme

I was analyzing repeated measures data with linear mixed models with the lmer function, but due to heavy tailed residuals (image below) I am now using the heavyLme function. I wanted to compare the ...
0
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0answers
8 views

Meaning of an odds ratio in mixed effects logistic regression

Pardon my ignorance but I am looking for some statistics help. I ran a mixed effects logistic regression and produced a summary table in R. Because of the nature of the regression type I don't have ...
0
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0answers
15 views

How can I take out all the values lying near the QQ-line? [closed]

QUESTION: Objective: I want to find out the distribution function F of Facebook's return Method: I estimate the empirical CDF with Gaussian kernel method for the interior of the distribution and POT ...
0
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0answers
7 views

Ljung Box Test Interpretation Strange Results

Sorry for my mistakes or the combination of my phrases, I am French. So, I am currently working on daily time series, and I had to build a SARIMAX model. After testing different combinations for the ...
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0answers
12 views

How can I include variables as predictors but not variables to be imputed in multiple imputation with Amelia?

I am using Amelia for multiple imputation, and have a very large list of variables to predict missingness in my exposure and outcome. However, I don't want to impute values in these predictors, I only ...
0
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0answers
18 views

How to compute the covariance matrix of a multivariate bernoulli distribution?

Considering this toy example: Let $x$ be a random variable $x \sim \mathcal{N}(\mu_x, \Sigma_x)$ Where $\mu_x \in \mathbb{R}^2$ is the mean vector and $\Sigma_x \in \mathbb{R}^{2 \times 2}$ is the ...
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0answers
9 views

Summarize attention weights from different Transformer blocks

I am dealing with a full seq2seq Transformer. Both the encoder and decoder are composed of different stacked blocks. In each of them, different kinds of attention mechanisms are employed (self-...
0
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0answers
12 views

How to implement LSTM backpropagation through time?

I'm building a custom LSTM net based on this article. I got questions on how to implement the backpropagation, based on these formulas of the derivatives in an LSTM layer: Question 1: The weights (w.....
-1
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0answers
7 views

Comparing results obtained from a within-subject with those from a between-subject design [closed]

We have data from two similar studies. One was conducted as a one-way between-subject study. The other was a within-subject study on the same independent variable. Aside from the design, the between ...
1
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1answer
22 views

Correlation between two constant variables using the different approaches [duplicate]

Let's say we have a vector X = (1, 1, 1) and Y = c(2, 2, 2). I want to calculate correlation between those. Taking Pearson ...
0
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0answers
16 views

Squaring random variable, with accurate definition [closed]

If I need to calculate $\mathrm{E}(X^2)$ and I have discrete finite pdf, can I represent $X^2$ by creating another random variable $Y = X^2 $,and here is my question; Do I just multiply every element ...
1
vote
1answer
15 views

Can we use the binomial distribution instead of Bonferroni correction for large number of independent significant tests?

Supposing we are doing e.g 1000 one-sample t-tests with the null hypothesis that all population means are 0, with significance level 0.01. One common method for dealing with the number of tests is to ...
0
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0answers
11 views

Correlations comparison between trialgroup and controlgroup using SPSS

I am new this community site and I need your help. The data below needs to find out how to get correlations pairs between trial group_store_NBR (store1 as 5) and control group_store_NBR. ...
0
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0answers
9 views

Comparing the interaction coefficient of a poisson regression to both of the individual variables?

I have a Poisson regression of the form $$\log(y) = \beta_0 + \beta_1x_1 + \beta_2x_2 + \beta_3x_1x_2 + \cdots,$$ where $x_1$ is a binary variable indicating the presence of exposure 1, and $x_2$ ...
1
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0answers
21 views

Statistical test to tell whether multiple samples come from the same distribution type

I have many samples $S_1,S_2,\dots ,S_n$. Each sample consists from different number of observations $O_1,O_2,\dots,O_n$. Now I want to conclude that all samples come from the same distribution type (...
0
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0answers
8 views

What is the most efficient way of adding values from different scales to create a metric? Normalization v/s Scaling v/s?

I'm working on creating a metric to evaluate medical protocols with different factors. The proportion of weightage of each factor is determined by a survey which we have calculated as below : Factor a ...
0
votes
1answer
19 views

What are the assumptions that need to be checked for multilevel logistic regression and for multilevel ordinal logistic regression

I am running multilevel models for panel data on a binary outcome (mixed logistics regression) and on a ordinal outcome (mixed ordinal logistic regression). I am aware that for example with a mixed ...
1
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0answers
21 views

What metrics can be used to evaluate each cluster in clustering

I am clustering a dataset, where the binary ground truth (positive/negative samples) is known. I am looking for specific clusters that show high homogeneity/purity. I know that there are many metrics ...
0
votes
1answer
17 views

Wilcoxon rank sum test or wilcoxon signed rank test?

I have recorded the the rate at which water exits a tank on-site and through a video recording and it looks something like this: Water Level Flow Rate (On-site) Flow Rate (Video) 0.60 1.70 1.62 0....
0
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0answers
4 views

how to test auto-selected sample and modify it to represent population

Suppose you have responses from a survey on an entire population, i.e. an organization of 5000 people. All has been invited to respond. Only 65% of them did. Assume also you have the ground truth of ...
0
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0answers
19 views

How to tell if performance gain for a model is statistically significant?

I am trying different tree models (different number of features) and getting the following result: I can identify the best model (red circle, Approach 1), but I would like to get the most ...
0
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0answers
7 views

Will the number of contrasts in orthogonal contrasts always be number of levels of the factors minus 1?

(I'm working in R) If I want to run a linear model on a dependent variable as a function of a categorical variable with 3 levels (l=3), and I want to use orthogonal contrasts, will I always have to ...
1
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0answers
15 views

Meta-Analysis (paired t-test)

I would like to combine within-study designs and between study designs in a meta-analysis. My research question is if movement interventions increase cognitive ability. So far, I have analyzed studies ...
0
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0answers
9 views

Present country differences in a variable [closed]

Suppose I measure some continious variable in three countries based on large quota-representative samples (+ using some post-stratification). What is the best way to present country differences ...
1
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0answers
15 views

Comparing non-parametric correlations

I have two correlation (Spearman's rho) matrices from a single sample (before/ after intervention) and I would like to compare them to see whether intervention changed each or some of these ...
0
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0answers
10 views

How is covariance matrix affected if each data points is multipled by some constant?

I have a 2D multivariate Normal distribution with some mean and a covariance matrix. While fitting the function I had normalized the data.so the mean and covariance I have are for the normalized data. ...
0
votes
1answer
23 views

If time reverses the Wide Sense Stationary(WSS) preserves or not?

If $X(t)$ is WSS with autocorrelation $R_{X}(\tau)$ then is $Y(t)=X(-t)$ WSS? How to find Cross Correaltion of $X(t)$ and $Y(t)$ too? And, can we say they are jointly WSS?
2
votes
1answer
35 views

If $y_t$ and $x_t$ are cointegrated, then are $y_t$ and $x_{t-d}$ also cointegrated?

Assume that $x_t, y_t$ are $I(1)$ series which have a common stochastic trend $u_t = u_{t-1}+e_t$. Particularly, consider the following DGP \begin{align} y_t&=\alpha_y+u_t+a_t \tag{1} \\ \end{...
0
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0answers
10 views

Multivariate Time series forecasting- Statistical methods

I was trying to forecast the truck numbers required at each distribution location...for that I was forecasting the shipments(number of units) at each location and dividing it by a factor to get the ...
0
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0answers
6 views

2SLS IV Estimation but second stage on a subsample

I have a simple but peculiar question. Let's say I have 100 observation. Am I allowed to estimate my endogenous variable by using 1-100 observations but only use 1-50 in my second stage? As the ...
1
vote
1answer
29 views

Hypothesis Testing Probability Density Estimates [closed]

Is there a good way to test an probability density estimate against observed data? I know there exist various approaches to probability density estimation and testing individual parameters of density ...
0
votes
0answers
9 views

Hotelling T squared seemingly useless at detecting a mean shift

I am trying to develop a single-sample hotelling $T^2$ test in order to implement a multivariate control chart, as described in Montgomery, D. C. (2009) Introduction To Statistical Quality Control, ...
0
votes
0answers
10 views

Vikneswaran R companion to experimental design datasets and similar books or companions [closed]

I am looking for something as comprehensive as Vikneswaran R companion to experimental design. It can include different tests with some theory and practicals with R. Do you know of any new similar ...
1
vote
1answer
14 views

Can the Fisher exact test be used to get a confidence interval for the efficiency of a vaccine (risk ratio or relative risk)?

Consider the Pfizer vaccine for COVID-19. The data from the phase 3 trials shows that they had 21720 people in the vaccinated group and 21728 people in the control group: ...
0
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0answers
6 views

In the case of the same SD, the difference between One sample t-test and Two sample t-test [duplicate]

In the case of the following program, I can think simply it has two times probability between One sample t-test(0.002111) and Two sample t-test(0.001053) to the p-value? ...

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