Panel Data Pre-Testing and Diagnostic Suite // Pre-testing and diagnostic tools for panel data analysis. Researchers should run these tests before any panel regression to verify modelling assumptions. The package implements: (1) the Hsiao (2014, ISBN:978-1-107-65763-2) homogeneity F-tests (F1/F2/F3), Swamy (1970) doi:10.2307/1913012 parameter heterogeneity test, and Pesaran (2004) doi:10.2139/ssrn.572504 cross-sectional dependence test via xtpretest(); (2) missing-data detection, mechanism testing, and imputation for unbalanced panels via xtmispanel(); (3) quantile-regression cross-sectional dependence tests (T_tau and T-tilde_tau statistics) of Demetrescu, Hosseinkouchack and Rodrigues (2023) doi:10.1016/j.jeconom.2022.09.001 via xtcsdq(); and (4) the panel quantile-regression slope homogeneity S-hat and D-hat statistics of Galvao, Juhl, Montes-Rojas and Olmo (2017) doi:10.1080/07350015.2015.1054493 via xtqsh(). Together these tests address three fundamental pre-testing questions: (i) are slopes homogeneous? (ii) is there cross-sectional dependence? and (iii) is the panel balanced and is missingness ignorable?