

VarCorr(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, stan-
     dard 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 inherit-
          ing 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 devia-
     tions, 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 correla-
     tions 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_:

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

