var.linear               package:boot               R Documentation

_L_i_n_e_a_r _V_a_r_i_a_n_c_e _E_s_t_i_m_a_t_e

_D_e_s_c_r_i_p_t_i_o_n:

     Estimates the variance of a statistic from its empirical influence
     values.

_U_s_a_g_e:

     var.linear(L, strata=NULL)

_A_r_g_u_m_e_n_t_s:

       L: Vector of the empirical influence values of a statistic. 
          These will usually be calculated by a call to 'empinf'. 

  strata: A numeric vector or factor specifying which  observations
          (and hence empirical influence values) come from which
          strata. 

_V_a_l_u_e:

     The variance estimate calculated from 'L'.

_R_e_f_e_r_e_n_c_e_s:

     Davison, A. C. and Hinkley, D. V. (1997) _Bootstrap Methods and
     Their Application_. Cambridge University Press.

_S_e_e _A_l_s_o:

     'empinf', 'linear.approx', 'k3.linear'

_E_x_a_m_p_l_e_s:

     #  To estimate the variance of the ratio of means for the city data.
     ratio <- function(d,w)
          sum(d$x * w)/sum(d$u * w)
     var.linear(empinf(data=city,statistic=ratio))

