sievePH is an R package implementing estimation and testing procedures described in: * Juraska M and Gilbert PB (2013). Mark-specific hazard ratio model with multivariate continuous marks: An application to vaccine efficacy. Biometrics 69, 328-337. PMCID: PMC3940058. * Juraska M and Gilbert PB (2016). Mark-specific hazard ratio model with missing multivariate marks. Lifetime Data Analysis, 22:606. PMCID: PMC4848257.