cd4 package:boot R Documentation _C_D_4 _C_o_u_n_t_s _f_o_r _H_I_V-_P_o_s_i_t_i_v_e _P_a_t_i_e_n_t_s _D_e_s_c_r_i_p_t_i_o_n: The 'cd4' data frame has 20 rows and 2 columns. CD4 cells are carried in the blood as part of the human immune system. One of the effects of the HIV virus is that these cells die. The count of CD4 cells is used in determining the onset of full-blown AIDS in a patient. In this study of the effectiveness of a new anti-viral drug on HIV, 20 HIV-positive patients had their CD4 counts recorded and then were put on a course of treatment with this drug. After using the drug for one year, their CD4 counts were again recorded. The aim of the experiment was to show that patients taking the drug had increased CD4 counts which is not generally seen in HIV-positive patients. _U_s_a_g_e: cd4 _F_o_r_m_a_t: This data frame contains the following columns: '_b_a_s_e_l_i_n_e' The CD4 counts (in 100's) on admission to the trial. '_o_n_e_y_e_a_r ' The CD4 counts (in 100's) after one year of treatment with the new drug. _S_o_u_r_c_e: The data were obtained from DiCiccio, T.J. and Efron B. (1996) Bootstrap confidence intervals (with Discussion). _Statistical Science_, *11*, 189-228. _R_e_f_e_r_e_n_c_e_s: Davison, A.C. and Hinkley, D.V. (1997) _Bootstrap Methods and Their Application_. Cambridge University Press.