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(object, sigma, rdig)

_A_r_g_u_m_e_n_t_s:

  object: 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 and Douglas Bates

_E_x_a_m_p_l_e_s:

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

