VarCorr                 package:nlme                 R Documentation

_E_x_t_r_a_c_t _v_a_r_i_a_n_c_e _a_n_d _c_o_r_r_e_l_a_t_i_o_n _c_o_m_p_o_n_e_n_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     This function calculates the estimated variances, standard
     deviations, and correlations between the random-effects terms in a
     linear mixed-effects model, of class 'lme', or a nonlinear
     mixed-effects model, of class 'nlme'. The within-group error
     variance and standard deviation are also calculated.

_U_s_a_g_e:

     VarCorr(x, sigma, rdig)

_A_r_g_u_m_e_n_t_s:

       x: a fitted model object, usually an object inheriting from
          class 'lme'.  

   sigma: an optional numeric value used as a multiplier for the
          standard deviations. Default is '1'. 

    rdig: an optional integer value specifying the number of digits
          used to represent correlation estimates. Default is '3'. 

_V_a_l_u_e:

     a matrix with the estimated variances, standard deviations, and
     correlations for the random effects. The first two columns, named
     'Variance' and 'StdDev', give, respectively, the variance and the
     standard deviations. If there are correlation components in the
     random effects model, the third column, named 'Corr', and the
     remaining unnamed columns give the estimated correlations among
     random effects within the same level of grouping. The within-group
     error variance and standard deviation are included as the last row
     in the matrix.

_A_u_t_h_o_r(_s):

     Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates
     bates@stat.wisc.edu

_R_e_f_e_r_e_n_c_e_s:

     Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S
     and S-PLUS", Springer, esp. pp. 100, 461.

_S_e_e _A_l_s_o:

     'lme', 'nlme'

_E_x_a_m_p_l_e_s:

     fm1 <- lme(distance ~ age, data = Orthodont, random = ~age)
     VarCorr(fm1)