STATISTICAL ASSESSMENT OF SAMPLING VARIABILITY AND CONFIDENCE INTERVAL COVERAGE USING BOOTSTRAP METHODS

Authors

  • Dr. Emily Carter Department of Statistics and Probability, Northbridge Institute of Mathematical Sciences, United Kingdom
  • Dr. Lukas Schneider Department of Applied Mathematics, Rhine Valley Institute of Technology, Germany
  • Dr. Sofia Laurent Department of Statistical Modelling and Data Science, Westlake Research Institute, Canada

DOI:

https://doi.org/10.69980/84g63842

Keywords:

Bootstrap Resampling, Sampling Variability, Confidence Interval Coverage, Monte Carlo Simulation, Statistical Inference

Abstract

Bootstrap resampling is widely applied to statistical inference to estimate the sampling variability and derive confidence intervals. In small-scale studies, however, its reliability may be affected by the sample size, probability distribution and estimation uncertainty. The purpose of this study was to assess the sampling variability, estimation accuracy and empirical coverage of the confidence intervals from sample-based statistical powers in the different simulation conditions. The study is of quantitative, simulation type with secondary data that is publicly available from Zenodo. Thirty-six conditions—three probability distributions (normal, skewed, and ceiling/discrete), four effect sizes, and three different pilot sample sizes (10, 15, and 20 per group) were analysed. There were 400 stand-alone pilot simulations with 400 bootstrap replications per pilot simulation per condition. The statistical performance was evaluated by standard deviation, estimation bias, root mean squared error (RMSE) and empirical coverage of confidence intervals. Results indicated that sampling variability (standard deviation between pilots) decreased as the number of samples collected in a pilot increased (0.2856 to 0.2179). The RMSE of Bootstrap also decreased from 0.3281 to 0.2363, indicating better estimation accuracy. However, its empirical mean coverage was as low as 14.37% as opposed to the nominal level of 95%. These results highlight the need to consider the various sources of uncertainty and improve the calibration of confidence intervals to obtain more reliable statistical inference using the bootstrap in small-sample studies.

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Published

2025-09-30