##### Core dictionary (coreCIF) version 2.3.1

# _refine_ls_goodness_of_fit_obs

**Name:**

`'_refine_ls_goodness_of_fit_obs'`

This definition has been superseded and is
retained here only for archival purposes. Use instead
`'_refine_ls_goodness_of_fit_gt'`

**Definition:**

The least-squares goodness-of-fit parameter S for observed reflections (see _reflns_observed_criterion) after the final cycle of refinement. Ideally, account should be taken of parameters restrained in the least-squares refinement. See also _refine_ls_restrained_S_ definitions. { sum { w [ Y(obs) - Y(calc) ]^2^ } }^1/2^ S = { ----------------------------------- } { Nref - Nparam } Y(obs) = the observed coefficients (see _refine_ls_structure_factor_coef) Y(calc) = the calculated coefficients (see _refine_ls_structure_factor_coef) w = the least-squares reflection weight [1/(u^2^)] u = standard uncertainty (e.s.d.) Nref = the number of reflections used in the refinement Nparam = the number of refined parameters and the sum is taken over the specified reflections

The permitted range is 0.0 -> infinity

**Related item: **

**Type:** numb

**Category:** refine