bdf package:nlme R Documentation _L_a_n_g_u_a_g_e _s_c_o_r_e_s _D_e_s_c_r_i_p_t_i_o_n: The 'bdf' data frame has 2287 rows and 25 columns of language scores from grade 8 pupils in elementary schools in The Netherlands. _U_s_a_g_e: data(bdf) _F_o_r_m_a_t: _s_c_h_o_o_l_N_R a factor denoting the school. _p_u_p_i_l_N_R a factor denoting the pupil. _I_Q._v_e_r_b a numeric vector of verbal IQ scores _I_Q._p_e_r_f a numeric vector of IQ scores. _s_e_x Sex of the student. _M_i_n_o_r_i_t_y a factor indicating if the student is a member of a minority group. _r_e_p_e_a_t_g_r an ordered factor indicating if one or more grades have been repeated. _a_r_i_t_P_R_E_T a numeric vector _c_l_a_s_s_N_R a numeric vector _a_r_i_t_P_O_S_T a numeric vector _l_a_n_g_P_R_E_T a numeric vector _l_a_n_g_P_O_S_T a numeric vector _s_e_s a numeric vector of socioeconomic status indicators. _d_e_n_o_m_i_n_a a factor indicating of the school is a public school, a Protestant private school, a Catholic private school, or a non-denominational private school. _s_c_h_o_o_l_S_E_S a numeric vector _s_a_t_i_p_r_i_n a numeric vector _n_a_t_i_t_e_s_t a factor with levels '0' and '1' _m_e_e_t_i_n_g_s a numeric vector _c_u_r_r_m_e_e_t a numeric vector _m_i_x_e_d_g_r_a a factor indicating if the class is a mixed-grade class. _p_e_r_c_m_i_n_o a numeric vector _a_r_i_t_d_i_f_f a numeric vector _h_o_m_e_w_o_r_k a numeric vector _c_l_a_s_s_s_i_z a numeric vector _g_r_o_u_p_s_i_z a numeric vector _S_o_u_r_c_e: _R_e_f_e_r_e_n_c_e_s: Snijders, Tom and Bosker, Roel (1999), _Multilevel Analysis: An Introduction to Basic and Advanced Multilevel Modeling_, Sage. _E_x_a_m_p_l_e_s: summary(bdf)