Cox Snell pseudo r-squared.
References
Cox, D. R., & Snell, E. J. (1989). The analysis of binary data (2nd ed.). London: Chapman and Hall.
Maddala, G. S. (1983). Limited dependent and qualitative variables in economics. New York: Cambridge Press.
See also
Other model fit statistics:
blr_model_fit_stats(),
blr_multi_model_fit_stats(),
blr_pairs(),
blr_rsq_adj_count(),
blr_rsq_effron(),
blr_rsq_mcfadden_adj(),
blr_rsq_mckelvey_zavoina(),
blr_rsq_nagelkerke(),
blr_test_lr()