Study finds unsupervised imputation before cross-validation can reduce computational costs without significantly degrading model performance.
problem High computational costs in pipeline modeling algorithms with imputation steps.
method Empirical assessment of unsupervised imputation before vs during cross-validation.
result Reduced variance of imputation before cross-validation leads to lower overall root mean squared error.
Proposes a new method for logistic PCA to avoid overfitting.
problem Overfitting in logistic PCA for binary data.
method Non-convex singular value thresholding for logistic PCA.
result Proposed method outperforms models with convex penalties.
Trajectory-wise CVs reduce variance in policy gradient methods.
problem High variance in estimating policy gradient estimates.
method Proposes trajectory-wise control variates to reduce variance without bias.
result Trajectory-wise CVs are optimal for variance reduction under reasonable assumptions.
Temporal Difference learning or TD(λ) is a fundamental algorithm in the field of reinforcement learning. However, setting TD's λ parameter, which controls the timescale of TD updates, is generally left up to the practitioner. We formalize the λ selection problem as a bias-variance trade-off where the solution is …
Stochastic GD converges linearly for CV@R learning under certain conditions.
problem Optimizing CV@R in statistical learning with non-convex loss functions.
method Stochastic Gradient Descent with Polyak-Łojasiewicz condition.
result Stochastic GD achieves linear convergence for CV@R learning.
Ridge regression CV loss may have multiple local optima.
problem Can we globally optimize cross-validation loss in ridge regression?
method Analyzing quasiconvexity of CV loss in ridge regression.
result CV loss may fail to be quasiconvex and have multiple local optima.
Enhances diffusion-based sampling for molecular systems.
problem Inefficiency and thermodynamic mode miss in diffusion-based samplers for molecular systems.
method Introduces a sequential bias along collective variables (CVs) to encourage exploration and increase temperature in the projected space.
result Improves efficiency, mode discovery, and free energy estimation; first to demonstrate reactive sampling.
We consider a simple investment project with the following parameters: I>0: Initial investment which is amortizable in n years; n: Number of years the investment allows production with constant output per year; A>0: Annual amortization (A=I/n); Q>0: Quantity of products sold per year; Cv>0: Variable cost per unit; p>0:…
K-fold CV improves machine learning model selection but faces challenges with small datasets.
problem Challenges in validating machine learning models, especially with small datasets.
method K-fold cross-validation with K-fold CUBV (Upper Bound of the actual risk) and Upper Bound of the actual risk for linear classifiers.
result K-fold CUBV is a robust criterion for detecting effects and validating accuracy values from machine learning models.
This work improves confidence intervals for Cox model test error using nested CV.
problem Insufficient understanding of confidence intervals for cross-validation in Cox model.
method Generalized nested cross-validation to Cox proportional hazards model.
result Improved coverage of confidence intervals for Cox model test error.
Upper bounds for CV errors apply to lasso and other models.
problem Bounding CV errors for lasso and similar models.
method Rademacher complexity and Orlicz-Ψν norm. result Upper bounds are tight and stable for lasso.
CV outperforms mean-variance for stock returns, minimizing risk and maximizing growth.
problem Traditional risk assessment methods underperform in stock market analysis.
method Derived new CV equation and used it to analyze stock performance.
result Stocks with low but positive CV grow exponentially, outperforming high-risk stocks.
We prove that for k≥5 there does not exist a continuous map ∂CV(Fk)→PCurr(Fk) that is either Out(Fk)-equivariant or Out(Fk)-anti-equivariant. Here ∂CV(Fk) is the "length-function" boundary of Culler-Vogtmann's Outer space CV(Fk), and PCurr(Fk) is the space of pr…
Cross-validation (CV) is often used to select the regularization parameter in high dimensional problems. However, when applied to the sparse modeling method Lasso, CV leads to models that are unstable in high-dimensions, and consequently not suited for reliable interpretation. In this paper, we propose a model-free cri…
Optimal clustering handles missing values without imputation.
problem Missing values complicate clustering algorithms in biomedical studies.
method Integrates missing value mechanism into optimal clustering framework.
result Superior performance compared to other clustering approaches.
New method approximates CV for model assessment and selection.
problem Efficient model assessment and selection with large number of folds.
method Approximates expensive refitting with a single Newton step warm-started from full training set optimizer.
result Uniform non-asymptotic, deterministic model assessment guarantees for approximate CV.
Gaussian Processes improve missing value imputation in datasets.
problem Handling missing values in large datasets.
method Sparse Gaussian Processes combined with stochastic variational inference.
result MGP significantly outperforms other imputation methods.
The paper analyzes cross-validation for correlated data and introduces a bias-corrected estimator.
problem Cross-validation with squared error loss assumes independent and identically distributed (i.i.d.) data, which is often violated in correlated data.
method The paper presents a criterion for standard CV suitability and introduces a bias-corrected estimator (CVc) for correlated data. result The bias-corrected estimator (CVc) yields an unbiased estimate of prediction error in settings where standard CV is invalid. New method approximates CV efficiently for large-scale problems.
problem High computational cost of standard CV in large-scale problems.
method Iterative first-order algorithm to approximate CV solution.
result Extends CV approximation guarantees to non-converged solutions.
This work simplifies SVM parameter selection using S&S ratio.
problem SVM parameter tuning for optimal performance.
method S&S ratio to model SVM performance; automatic RP, kernel, and parameter selection.
result Optimized SVM parameters with reduced computational complexity.
IFGAN uses feature-specific GANs for missing value imputation.
problem Missing value imputation in data mining.
method Feature-specific Generative Adversarial Networks (GAN).
result IFGAN outperforms state-of-the-art algorithms in various missing conditions.
CV inference can be invalid for relatively unstable model comparisons.
problem The validity of cross-validation for model comparison is questioned when models are relatively unstable.
method The study proves that simple, individually stable models can generate relatively unstable comparisons, invalidating CV inference.
result The Lasso and soft-thresholding generate relatively unstable comparisons, invalidating CV inferences.
A method to approximate cross-validation for manifold regularization in semi-supervised learning.
problem Efficiency of cross-validation in selecting hyper-parameters for manifold regularization.
method Using Bouligand influence function (BIF) for Taylor expansion to approximate cross-validation.
result The proposed method significantly improves efficiency with minimal time cost.
Geometric study of Outer Space using envelopes and geodesics.
problem Understanding the geometry and structure of Outer Space CVn. method Study of envelopes in the asymmetric Lipschitz metric of CVn. result For almost all pairs of points in CVn, their envelopes have dimension 3n−4. New CVs preserve transition rates in molecular dynamics.
problem Designing CVs that accurately capture rare events in high-dimensional systems.
method Integrating manifold learning and group-invariant featurization to construct neural network-based CVs that satisfy orthogonality conditions.
result Achieved a CV for butane that reproduces the anti-gauche transition rate with less than ten percent relative error.
New method learns collective variables using autoencoders for molecular simulations.
problem Learning low-dimensional slow degrees of freedom (collective variables) for molecular simulations.
method Iterative method involving CV learning with autoencoders and reweighting scheme.
result Achieves convergence of learned collective variables.
kNNSampler imputes missing values from their distributions using kNN.
problem Impute missing values from their distributions.
method Randomly samples from the observed responses of the k most similar units.
result Estimates the conditional distribution of missing values.
DeepIFSAC uses attention mechanisms and contrastive learning to impute missing values in tabular data.
problem Missing values in tabular data, especially when high and not random.
method Row and column attention in a contrastive learning framework with CutMix data augmentation.
result Proposed method outperforms state-of-the-art methods for missing rates between 10% and 90% and various missing value types.
Careful tuning of a regularization parameter is indispensable in many machine learning tasks because it has a significant impact on generalization performances. Nevertheless, current practice of regularization parameter tuning is more of an art than a science, e.g., it is hard to tell how many grid-points would be need…
Consistent supervised learning with missing values is possible using imputation or specialized models.
problem Predicting with missing values in both training and testing data.
method Two approaches: imputing with a constant and using a predictor for complete observations through multiple imputation. Decision trees can handle missing values naturally.
result Imputing with a constant can be consistent when missing values are not informative.
Double autoencoder Ae2I improves missing value imputation in recommender systems.
problem Imputing missing values in tables using row-row and column-column relationships.
method Simultaneously uses row-row and column-column relationships through a double autoencoder.
result Ae2I outperforms state-of-the-art models in recommender systems. ELMV uses ensemble learning to handle missing values in EHR data.
problem Significant missing values in EHR data cause bias and unreliable conclusions.
method ELMV constructs multiple subsets with lower missing rates and uses a support set for ensemble learning.
result ELMV outperforms conventional methods in critical feature identification and outcome prediction.
Meta-CVs leverage task similarity to reduce variance with limited data.
problem Reducing variance in Monte Carlo estimators with few samples.
method Meta-learning control variates for related tasks.
result Meta-CVs lead to significant variance reduction in settings with limited data.
LGnet jointly models local and global dynamics for MTS forecasting with missing values.
problem Missing values in multivariate time series data.
method LGnet framework using memory network and adversarial training.
result LGnet effectively forecasts MTS with missing values and robust under various missing ratios.
A new imputation method considers feature importance for missing value completion.
problem Missing values in datasets reduce accuracy and increase processing difficulty.
method Iterative matrix completion with feature importance learning.
result The method outperforms existing imputation algorithms on various datasets.
A new imputation method MissARF uses adversarial random forests for fast and accurate missing value imputation.
problem Handling missing values in biostatistical analyses.
method Adversarial Random Forests (ARF) for density estimation and data synthesis.
result MissARF performs comparably to state-of-the-art methods in imputation quality and runtime.
New algorithms handle missing data to improve fairness in machine learning.
problem Missing values in data can lead to unfair outcomes in machine learning models.
method Developed scalable and adaptive algorithms to handle missing values while preserving predictive information.
result Our adaptive algorithms consistently achieve higher fairness and accuracy than standard impute-then-classify methods.
For the free group FN of finite rank N≥2 we construct a canonical Bonahon-type continuous and Out(FN)-invariant \emph{geometric intersection form} \[ <, >: \bar{cv}(F_N)\times Curr(F_N)\to \mathbb R_{\ge 0}. \] Here cvˉ(FN) is the closure of unprojectivized Culler-Vogtmann's Outer space cv(FN)…
New CV method reduces bias in spatial prediction models.
problem Bias in standard cross-validation due to uneven sampling.
method Target-Weighted Cross-Validation (TWCV) framework.
result Weighted CV approaches reduce bias in prediction error.
RDIS fills missing values in time series data explicitly.
problem Missing values in time series data.
method Random Drop Imputation with Self-training.
result RDIS achieves competitive results on real-world datasets.
A method for efficient CV estimates in Bayesian hierarchical models.
problem Computational infeasibility of cross-validation in Bayesian hierarchical regression models.
method Conditioning on variance-covariance parameters to transform CV into an optimization problem.
result Equivalent or improved predictive estimates compared to full cross-validation.
Extending spatio-temporal scale limitations of models for complex atomistic systems considered in biochemistry and materials science necessitates the development of enhanced sampling methods. The potential acceleration in exploring the configurational space by enhanced sampling methods depends on the choice of collecti…
Paper tackles linear models with missing values, achieving minimax optimal results.
problem Missing values in real-world data complicate linear model learning.
method Proposes a rigorous setting and a new algorithm leveraging missing data distribution.
result Derives minimax optimal adaptive risk bounds for predictions with missing values.
Proposes rCV to preserve serial correlations in time-series models.
problem Loss of serial correlations in cross-validation for time-series models.
method Form k folds, generate k new partial time-series, reconstruct using imputation/smoothing, build primary models, evaluate performance.
result Avoids loss of serial correlations and preserves non-stationarity in predictions.
Imputation-free method learns tabular data with missing values using transformer.
problem Machine learning on tabular data with missing values often leads to unreliable outcomes due to synthetic imputation.
method Incremental attention learning (IFIAL) using transformer with attention masks.
result IFIAL outperforms state-of-the-art methods in 17 diverse tabular data sets.
Proposes a method to handle missing inputs in Bayesian optimization.
problem Missing values in historical data and function evaluations.
method Impute missing values using probability distributions and develop a new acquisition function.
result Improves performance of Bayesian optimization by handling missing inputs effectively.
Sparse regression such as the Lasso has achieved great success in handling high-dimensional data. However, one of the biggest practical problems is that high-dimensional data often contain large amounts of missing values. Convex Conditioned Lasso (CoCoLasso) has been proposed for dealing with high-dimensional data with…
Missing values widely exist in many real-world datasets, which hinders the performing of advanced data analytics. Properly filling these missing values is crucial but challenging, especially when the missing rate is high. Many approaches have been proposed for missing value imputation (MVI), but they are mostly heurist…