Within-Period Contraction of Atomic-Radius Residual Spread: Data, Code, and Preregistration

Complete data, code, and preregistration materials for a four-model falsifiable comparator test examining whether atomic-radius residuals contract systematically within periods 4-7 among non-f-block elements. Result: SUPPORTED (lambda_nf = -2.377, p = 0.0027, LOPO 4/4). Archive includes: analysis script (~590 lines, raw NumPy OLS), 118-element dataset, preregistration document, machine-readable results, and publication figures.