WP-1325 out of sample: TOPAS laws on WO3 refitted alone, against the untied fit
machine   Darwin arm64, 10 CPUs, python 3.12.10, numpy 2.5.4
rietx     1.10.0.dev0 at 7d7cb7bc, compiled kernels on
load      54.20 55.47 65.82
laws      ['m_c', 't_a', 't_beta', 'p_c'], each alone over all 100 patterns
m_c       4883.9 s converged iters [2, 5, 36, 213]; χ² 1335992.1 with 2902 free; alone    190.9 /  98 dof (cut  122.1,  1.95/dir, p 6.01e-08) REJECT
t_a       1909.9 s converged iters [2, 5, 21, 128]; χ² 1334666.8 with 2902 free; alone     62.8 /  98 dof (cut  122.1,  0.64/dir, p 0.998) keep

the comparison, from the per-law lines in wo3_each_results.txt
against the untied fit read from wo3_form_results.txt: χ² 1333788.3 with 3000 free, χ²r·f² 19.253; the all-laws fit's χ²r·f² 19.577
  m_c      refit Δχ²    2203.8 for  98:   114.5 (1.17/dir, p 0.122)
           all-laws freed 137.2 /  98 dof (cut  122.1,  1.40/dir, p 0.00556) REJECT; its gain    2686.0 (1.22 of the refit)
           the law-alone fit's own reading 190.9 /  98 dof (cut  122.1,  1.95/dir, p 6.01e-08) REJECT
  t_a      refit Δχ²     878.5 for  98:    45.6 (0.47/dir, p 1)
           all-laws freed 12.9 /  98 dof (cut  122.1,  0.13/dir, p 1) keep; its gain     252.5 (0.29 of the refit)
           the law-alone fit's own reading 62.8 /  98 dof (cut  122.1,  0.64/dir, p 0.998) keep
