# All Questions

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### Understanding Particle Filter

I have some questions about Particle filters. According to https://www.it.uu.se/katalog/andsv164/Teaching/Material/PF_Intro_2014_AndreasSvensson.pdf particle filtering is about computing the ...
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### In the most basic sense, what is marginal likelihood?

I understand that likelihood differs from a probability distribution because likelihood describes the probability of certain parameter values given the data that you've observed (it's essentially a ...
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### Selecting exogenous factors lag to develop an ARIMA model for daily forecasts

We are trying to assess the possible effect of some meteorological variables on cumulatives reported cases of the actual covid-19 disease for a wide range of countries at the daily timestep. Then, ...
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### Caret Metric RMSE not applicable for classification models when data is continuous but has an observation equal to 0

I am running into an error trying to train a caret model with method='glmnet.' My data is continuous and I am trying to do a LASSO regression, but the existence of a 0 for one of the observations is ...
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### Fasttext and new character not seen in training

Trying to understand how fasttext handles seeing a character in a test environment that it never saw in training. Specifically, I’ve been given a dataset to train a model where someone removed all of ...
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### Forecasting Sales using Prophet in R

could someone please help me figure out how to adjust my code so that it gives better predictions? Right now they are way to high. I'm wondering if it is something to do with the holiday lag. I'm not ...
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### Forecast Fit always one step forward

everything good? I'm making a projection using time series, but I have a problem that I can't solve. My forecast fit is always one step (month) ahead of my data. What I mean by this? The movement of ...
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### Interpolation of Hessian matrix

I have a model where hessian matrices are calculated along a path. Since the calculation is done using finite differences, this is very time consuming. I have tried to calculate only every second ...
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### Influence of TV spots on the number of visits to the website (time series problem)

I have hourly data regarding the number of visits to the website. A single record consists of date, time(0-23) and number of visits. In a separate table I have data about the display of advertising ...
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### NLP Classification over Taxonomy

I have a massive pool of data where each row maps a user-entered description to a code that classifies the mission that the description describes. I am trying to develop a model that at least helps ...
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### Predicting training time using randomly generated datasets

Given a dataset, I need to predict the amount of time it will take to fit a model to it. I plan to do this by creating a csv containing the logs of previously fit models, and passing that data itself ...
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### taking the radius neighborhoods of the points and joining them With R [closed]

I am trying to create the codes for the image below in R but failed. In short, we create their neighborhoods by taking certain radii on the points. then we connect the neighborhoods with the correct ...
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### Sample size needed for a survey with multiple questions

I want to make a survey with several questions and conclude those results for the whole population. For example, I want to estimate the following questions for my 1 million population : "do you ...
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### Can I conduct a weighted regression if I have one observation per year?

I am conducting a word analysis project where I find the relative frequency of a certain word over time in a corpus of film reviews. The corpus changes in size over time so someone suggested to me ...
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### How to determine if 2 specific variables should be in the regression at the same time [closed]

I am trying to run a regression and I have two variables; income and gender. How can I determine if these 2 regressors should be in the model at the same time? Is there some sort of a test?
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### numpy eigenvector and eigenvalues not making sense [closed]

sorry, maybe the subject is too strong? but its driving my little brain crazy ..please look at the code below ...
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### Is it preferable to subset data to test specific hypotheses or specify a full model and run contrasts?

Let's say I have a 2x2 design where participants are either in condition A or condition B and, within each condition, either get exposed to exposure C or exposure D. First, I want to test whether ...
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### Correlation between nominal and ordinal variables

In my survey data I have two variables: One is an ordinal variable with 5-scale scoring from Agree to Disagree. My second variable is an nominal variable where the participants had to choose from 7 ...
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### LR test for overlapping return data using bootstrap

I wish to test a null hypothesis as in Christoffersen (1998) to see whether a sequence of Value-at-Risk forecasts $Q_t(p) \in \mathcal{F}_t$ possesses correct conditional coverage. Here $p \in [0,1]$ ...
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### Expectation and variance of order statistics (x(n)-x(1))

I saw a solution for Expectation and variance of range (x(n)-x(1)) uniform $\mathcal U(0,\theta)$ from Ben. Namely: $$f_{R_{n}}(r)=\frac{1}{2θ}⋅Beta(r2θ∣n−1,2)$$ From this expression, we get the ...
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### Using both fixed effects and random effects in r metafor package

Hi there :) I am trying to run a meta analysis using rma.uni in the metafor package in r but cannot work out how to add both fixed effects (eg bird migration status) and random effects (eg species, ...
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### Can I use a binary logistic regression for repeated measures data?

For this particular study, I had 3 monkeys complete 3 tasks, each task has a binary outcome (Win/Lose). A task is considered complete when they reach a criterion of 85% accuracy in their most recent ...
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### Interpreting classification metrics for multiclass imbalance

I am at the point of reporting my results in a research article conducted. The dataset is highly imbalanced with class 1 and ...
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### How to interpret cokurtosis results?

I calculated a cokurtosis matrix of the returns of multiple stocks. I obtained the following results but not sure how to interpret them. I understand that when two random variables exhibit a high ...
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### Poor classification performance on a balanced dataset

I am trying to build a Stock Trend Prediction model (Target variable is 1 if the price goes up the next day and 0 if it goes down). The dataset consists 2724 samples and 60 features. Th data was split ...
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### A question about fisher's z transformation detail of his paper published in 1921

Typically, people will use Fisher's z-transformation (arctan) to turn the r into a variable that is approximately normally distributed. When I look though his paper published in 1915(https://www.jstor....
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### Nonparametric estimation of ranking data [closed]

Suppose I have $\{X_i, Y_i, N_i\}$, where $N_i$ is the number of objects for sample $i$, $Y_i$ is ranking (ordering or permutation) of $N_i$ objects, and $X_i = (X_{i1},\cdots, X_{iN_i})$ is a vector ...