Subgroup interactions in the Heart and Estrogen/Progestin Replacement Study: lessons learned.
Furberg CD, Vittinghoff E, Davidson M, Herrington DM, Simon JA, Wenger NK, Hulley S. Subgroup interactions in the Heart and Estrogen/Progestin Replacement Study: lessons learned. Circulation. 2002 Feb 26; 105(8):917-22.