ValCurvaR - Validation of Analytical Calibration Curves

Provides transparent tools for fitting and evaluating analytical calibration curves. Ordinary and weighted least squares fits are supported, together with lack-of-fit, heteroscedasticity and influence diagnostics, back-calculation, prediction uncertainty and publication-ready base graphics. The workflow is designed to support validation studies rather than rely on a single goodness-of-fit statistic. Methods follow Magnusson and Ornemark (2014) <https://www.eurachem.org/images/stories/Guides/pdf/MV_guide_2nd_ed_EN.pdf> and International Council for Harmonisation (2023) <https://database.ich.org/sites/default/files/ICH_Q2%28R2%29_Guideline_2023_1130_ErrorCorrection_2025.pdf>.