Nitrendipene package:nlme R Documentation _A_s_s_a_y _o_f _n_i_t_r_e_n_d_i_p_e_n_e _D_e_s_c_r_i_p_t_i_o_n: The 'Nitrendipene' data frame has 89 rows and 4 columns. _F_o_r_m_a_t: This data frame contains the following columns: _a_c_t_i_v_i_t_y a numeric vector _N_I_F a numeric vector _T_i_s_s_u_e an ordered factor with levels '2' < '1' < '3' < '4' _l_o_g._N_I_F a numeric vector _S_o_u_r_c_e: Bates, D. M. and Watts, D. G. (1988), _Nonlinear Regression Analysis and Its Applications_, Wiley, New York.