Routines for Fit, Inference and Diagnostics in Linear L1 and LAD Models R package diagL1 version 1.0.1 Diagnostics for linear L1 regression (also known as LAD - Least Absolute Deviations), including: estimation, confidence intervals, tests of hypotheses, measures of leverage, methods of diagnostics for L1 regression, special diagnostics graphs and measures of leverage. The algorithms are based in Dielman (2005) <doi:10.1080/0094965042000223680>, Elian et al. (2000) <doi:10.1080/03610920008832518> and Dodge (1997) <doi:10.1006/jmva.1997.1666>. This package builds on the 'quantreg' package, which is a well-established package for tuning quantile regression models. There are also tests to verify if the errors have a Laplace distribution based on the work of Puig and Stephens (2000) <doi:10.2307/1270952>. Software Depends: R (>= 3.6), quantreg (>= 6.1), greekLetters (>= 1.0.4) Imports: stats, methods, conquer, lawstat, MatrixModels, Matrix, MASS, cubature, doParallel, foreach Kevin Allan Sales Rodrigues <kevin.asr@outlook.com> Comprehensive R Archive Network (CRAN) Kevin Allan Sales Rodrigues [aut, cre] (ORCID: <https://orcid.org/0000-0003-4925-5883>), Silvia Nagib Elian [ctb, ths] GPL (>= 2) 2025-08-21 application/tgz https://CRAN.R-project.org/package=diagL1 doi:10.32614/CRAN.package.diagL1