Perform the Robust Multivariable Mendelian Randomization Analysis

Perform the robust multivariable Mendelian randomization 'robustMVMR' analysis in the two-sample Mendelian randomization setting. An example paper using the 'robustMVMR' package can be found in Yang et al. (2021) . In details, the 'robustMVMR' package produces both the robust estimators and the robust standard errors via the MM-estimates, which has been demonstrated to protect against heteroskedasticity, autocorrelation, and the presence of outliers in Yohai (1987) and Croux (2003) < https://EconPapers.repec.org/RePEc:ete:ceswps:ces0316>.