Questions tagged [down-sample]

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Resampling methods for curves and time series

In the case of imbalanced datasets, different oversampling/downsampling methods exist such as SMOTE, ADASYN, etc. However, this methods mostly simply interpolate in the feature space, treating the ...
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18 views

Downsampling before or after train/test split?

I've seen people split into train and test sets before applying upsample techniques (to only the training data), but applying downsampling to both training and test data (i.e. before the train/test ...
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1answer
19 views

Do ANOVA & MANOVA require balanced levels?

I have one independent variable with two levels, or categories, and four dependent variables. When doing a MANOVA or ANOVA test, how important is it for the number of observations in each category to ...
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37 views

While dealing with imbalanced classes, to what extent can we upsample a minority class? [duplicate]

I have my training data with the following approximate distribution: Negative events : 90,000 positive events : 5,000 Training a model would require to oversample the minority class (and might also ...
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51 views

Does downsampling decrease the entropy of the data?

Suppose we have an $n-dim$ time-series $X={x_1, x_2, \cdots, x_n}$ and we resample it to $m-dim$, $\hat{X}={\hat{x}_1, \hat{x}_2, \cdots, \hat{x}_m}$, where $m < n$. Can we say this downsampling ...
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22 views

Resampling imbalanced data in a multi-view scenario

Assume a multi-view scenario, where multiple views of the same entity are available. If each data pair is assigned a label and the resulting scenario is highly imbalanced, what are proper ways of ...
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36 views

should I resample/downsample the patients in the control arms?

I have retrospectively collected clinical data of two sets of patients, one set with the diagnosis of tumor A (group A) and the other with tumor B (group B). There're 90 patients in group A, and 1100 ...
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1answer
470 views

Is Tomek Link undersampling the same as Edited Nearest Neighbours with 1 neighbour?

From what I've read I've understood that undersampling the majority class with Tomek Links or Edited Nearest Neighbours with 1 neighbour should yield the same result. However, I've tried it on this ...
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183 views

Statistics of bootstrapped subsampled data

Scenario I have a treatment (T) and control (C) sample. In my T sample, I have 600 observations, and in my C sample, I have 250 observations. Because the number of observations might be important ...
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1answer
375 views

Convert predicted probabilities after downsampling to actual probabilities in classification

If I use undersampling in case of an unbalanced binary target variable to train a model, the prediction method calculates probabilities under the assumption of a balanced data set. I discovered two ...
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1answer
247 views

Kappa and downsampling, selection of data set

I have a unbalanced data set and use Cohen's kappa and AUC as performance measure. Without down sampling the Kappa value is around 0.85, with random down sampling it is 0.95. and with a house-made ...
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1answer
100 views

Correlation between vectors with non-matching y values without using interpolation

Is there a way to calculate the correlation between two time series that have been adaptively downsampled and thus (may) have different y values? This is easiest to explain with an example, so ...
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152 views

Does downsampling affect regression results?

How is linear regression affected by downsampling the explanatory variable? To be more precise, I would sort all the values of $x$, and then split into a a number bins with equal number of points in ...
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521 views

How to use cross validation when you have missing data & rare events?

I am trying to use repeated cross validation to test my classifier. Moreover, I want to use imputation due to missing values and downsampling due to unbalanced data (I have 88% of my data in the ...
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233 views

Bias from stratified sampling

Due to a lack of significance and the large size of the dataset (which had binomial responses with 20,000 responses out of a sample of 15,000,000) my peer has used random sampling to reduce the amount ...
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2k views

How to determine the correlation between data sets with the same period but different sample rates?

I am trying to determine the correlation between two sets of data points which span the same time period (20 minutes) but have different resolutions. The first set was recorded at 1-minute intervals, ...
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129 views

Numerical differentiation (derivative) and downsampling

I have some time course data which I would like obtain the first derivative of. As it seems quite difficult to model, I do not intend to fit a function to it, but rather compute the first derivative ...