Questions tagged [sampling]

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52 views

SuperLearner Cross validation with iid time series

I created a number of ML models in R and I aim at combining them to form an ensemble. I learned about SuperLearner library which cross validates many models and returns the weight to each model in ...
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30 views

Stratified selection based on the y response creates a bias in information (Berkson's bias)?

I have a database which has individuals in different months and a target variable which indicates wheter an event happened or not, let's say: ...
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2answers
104 views

Overfitted model produces similar AUC on test set, so which model do I go with?

I was trying to compare the effect of running GridSearchCV on a dataset which was oversampled prior and oversampled after the training folds are selected. The oversampling approach I used was random ...
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36 views

Difference between Gibbs sampling and variational Bayes inference

After reading in blogs and books, I came to the conclusion that Gibbs sampling and variation Bayes are methods for estimating or inference of posterior. Below link described but it's difficult to ...
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0answers
190 views

Training data requirements for NLP models

Are there general guidelines for how much data is required for natural language processing (NLP) classification models? I understand this may depend on the text quality, text length, how accurate the ...
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0answers
31 views

Resampling a normally distributed dataset for regression problems?

I have a dataset from an operating process having 5 measurements and 1 outcome. All values are normally distributed. When I train a regression model on the dataset it performs good on the majority of ...
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0answers
157 views

How to randomly sample crops from plain image with points only if crop contains n points inside?

Lets assume I have an image which only has white background and black points, all same size. I need to randomly sample crops with a hardcoded size. The condition is that all the crops need to contain ...
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0answers
39 views

Why Markov Chain Monte Carlo allows sampling from a large class of distributions and scales well with the dimensionality of the sample space?

How can I understand "Markov chain Monte Carlo allows sampling from a large class of distributions and which scales well with the dimensionality of the sample space"
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2answers
24 views

How to generate a random sample and distribute values based in an probability distribution?

I want to generate a random sample based on this probability distribution: The line is the KDE of the histogram. My random sample will have n values, the value is ...
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20 views

What's the order in applying SMOTE transformation in a pipeline?

Here's the thing, I have an imbalanced data and I was thinking about using SMOTE transformation. However, when doing that using a sklearn pipeline, I get an error because of missing values. This is my ...
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1answer
33 views

Training a Variational Autoencoder (VAE) for Random Number Generation

I have a complicated 20-dimensional multi-modal distribution and consider training a VAE to learn an approximation of it using 2000 samples. But particularly, with the aim to subsequently generate ...
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0answers
14 views

Sequential sampling from Gaussian conditional not working

I'm trying to sequentially sample from a Gaussian Process prior. The problem is that the samples eventually converge to zero or diverge to infinity. I'm using the basic conditionals described e.g. ...
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0answers
26 views

Generating artificial data to extend learning set

I have dataset containing 42 instances(X) and one final Y on which i want to perform LASSO regression.All are continuous and numerical. As the sample size small, I wish to extend it. I am kind of ...
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13 views

Adaptive Sampling Strategies for SVM?

I am an Engineer interested in creating a surrogate model of a certain phenomenon in the context of reliability engineering. Essentially my quantity of interest is the Limit state function/stability ...
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0answers
16 views

Uniform convergence garantee on sample complexity

I can't understand why the Uniform Convergence guarantees an upper bound and not a lower bound on sample complexity as stated on [1] Corollary 4.4. If a class $H$ has the uniform convergence property ...
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0answers
37 views

Chi Square Test Goodness of Fit

I want to use a chi square test but I'm unsure if I'm using it right. The KickStarter website shows the frequency of main categories projects. It is updated once a day. I got a data set of KickStarter ...
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1answer
19 views

How to draw a sample from data set with respect to a given categorical or numerical variable based on given freely chosen distribution? (Python)

Say I have a data set for some past period. Now new data appears and for a given variable in the data and we find that the distributions have shifted (for example with "age" it would be that suddenly ...
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1answer
58 views

How to estimate the accuracy on a large dataset?

Given that I have a deep learning model(handover from former colleague). For some reason, the train/dev set was missing. In my situation, I want to classify my dataset into 100 categories. The ...
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2answers
83 views

Bayesian network in Python: both construction and sampling

For a project, I need to create synthetic categorical data containing specific dependencies between the attributes. This can be done by sampling from a pre-defined Bayesian Network. After some ...
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1answer
25 views

Sampling trying to keep as much multivariate variance as possible

I was thinking if anyone considered a sampling technique that would try to aim keeping as much of the variance as possible (e.g. as many unique values, or very widely distributed continuous variables)....
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0answers
32 views

Which machine learning methods can be used to address MonteCarlo sampling problems?

I would like to pick the brains of machine learning experts here to point me to a branch of machine learning technique that is best suited for my context. I would like to estimate the average value $\...
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0answers
61 views

Variable Importance changes with oversampling

I am currently using Xgboost for a binary classification problem with highly imbalanced data in R. I have used oversampling to train the model. This worked well, now however it comes to measuring ...
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0answers
162 views

Relation between using stratify and class weights for imbalanced classes

I'm working on a multi-class classification problem where the classes are imbalanced (70:25:5). Train-Test Split ...
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0answers
21 views

SmoteBoost: Should SMOTE be ran individually for each iteration/tree in the boosting?

As per the paper on SmoteBoost, SMOTE is ran for each iteration of the boosting, generating N samples, which are further added to the original training data and the weight distribution of the ...
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1answer
85 views

Generating a set of different scenarios based on some initial observations

I have a in my hands 3 different time series which model 3 different scenarios (base, downside, upside). Every of this time-series depends on a set of 11 different attributes, which take values for ...
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386 views

Sample size equation for multi-class distribution

I have a large (k>15) number of potential classes involved in a text classification problem, and don't know the true distribution of these classes in the ...
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1answer
108 views

Downsample GPS track

I am working with GPS track files (list of X and Y coordinates). I have tracks with a high sampling rate and want to downsample the track for easier handling. The obvious way would be to create a new ...
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29 views

Search Query Sample Size Determination for validation set

While designing a search system, which searches in N identifiable categories, how many search queries does one need in each category to validate the target metric (DCG) scores accurately (balanced ...
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200 views

Orange: Group samples by a “splitting” feature for cross-validation?

I need to split my datasets based on my own feature column in order to hold together certain data rows (e.g. from one patient, or compound) for cross-validation (CV). In Orange 3.11, Test&Score ...
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0answers
27 views

Calculate accuracy of crowdsourced responses in realtime

I have a total dataset of, lets say, 1000 Items. Each item will get a response from the crowd. After I get all the 1000 responses, I can sample the dataset to calculate accuracy. Sampling would ...
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14 views

Negative downsampling for Text classification

I would need to calculate the negative downsampling for my dataset, which shows imbalanced classes. My dataset looks like ...
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0answers
16 views

Training a Variational Autoencoder (VAE) for Non-Uniform Random Number Generation

I have a complicated 20-dimensional non-uniform distribution and would like generate samples from it. I have considered training a VAE to do so, but my problems are the following: Is my approach ...
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0answers
11 views

Positive records : no behavioral data

0 I'm working on a classification model aimed at identifying if behavioral activity within an account (b2b - one account, many contacts) can predict or not an opportunity generation ( a salesperson ...
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0answers
24 views

Difference between test statistic and sample statistic?

Test statistic and sample statistic are used to check statistical significance. How do I understand the procedure in background of reaching a conclusion about an effect-size estimate.
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15 views

HR employee attrition modeling - making a balanced sample question

I have dataset 1 (stayers) consisting of 1500 record of HR data demographic data of employees (11 features) who currently are in the company. Dataset 2 (leavers) contains 180 records -same features- ...
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0answers
21 views

How to downsample a dataset with constraints in Python?

I have a dataset that has columns a, b, and others. Both a and ...
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1answer
12 views

Getting a balanced sample across many variables

Let’s say each element in my population has several attributes. Let’s call then A, B, C, D, E, F. Let’s say, for simplicity, each attribute has 10 values (but could be any number between 2 and 30). ...
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19 views

Question regarding strata in Geron's book

In the book "Hands-On Machine Learning with Scikit-Learn and Tensorflow" by Aurélien Géron. There is a regression project explained. My doubt is regarding his example for 'stratified sampling'. He ...
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0answers
25 views

Smote oversampling on strings

I have an imbalanced dataset with most transactions being OK and 1% transactions marked as fraud. This dataset has columns with integers (time and transaction amount and timestamp) as well as strings (...
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0answers
24 views

Time Series Model (n-beats paper) how is sampling / training done?

does any one know what this means? It is taken from the paper https://openreview.net/pdf?id=r1ecqn4YwB (n-beats time series model). To update network parameters for one horizon, we sample train ...
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1answer
26 views

Is there a name for this form of sampling?

I had an idea to combine oversampling and undersampling in the following way: Compute the average number of individuals in each class. For classes with a number of individuals greater than this ...
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21 views

dealing with imbalanced data for multi-class problem

Based on the experiments I run for a number of times, and the reading I did on imbalanced data for a multiclassification problem such as this paper, resampling techniques like ...
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0answers
9 views

Estimate machine count for API dependency

I have a SDK, with many APIs, which is used by many apps. Those apps are installed on many machines. I get data containing machine Id, app name and API info . The data is sampled such that 2% of the ...
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24 views

Imbalanced Data Classification

This is my code with which I tried to attack my imbalanced dataset from here. Now I have 2 questions. When I try to split my data into train/test data and try to run the table() function, I always ...
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0answers
125 views

undersampling problem in imblanced dataset ValueError: Unknown label type: 'continuous'

I would like to undersampling the data but I encounter the following error? ...
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1answer
112 views

Correctly evaluate model with oversampling and cross-validation

I'm dealing with a classic case of dataset with binary imbalanced target (event 3%, non event 97%). My idea is to apply some sort of sampling (over/under, SMOTE etc.) to address the issue. As I see, ...
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1answer
1k views

train_test_split ValueError: Input contains NaN

I tried to do a stratified sampling by way of train_test_split in order to save myself some trouble later. So I wrote the following lines: ...
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1answer
98 views

Sampling randomly from pd.DataFrame, but ignoring NaN values

I am trying to sample random values from a dataframe where the NaN values should be ignored, without dropping the entire row or column. My sampling function at the moment looks like this: ...
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1answer
351 views

Downsampling the dataset to create balanced dataset for neural models

I have a classification dataset with 10k instances and 4 classes and it is unbalanced. 7000 of it belongs to first class, 2000 of it belongs to second 800 of it belongs to third class and remaining ...