onions                package:SemiPar                R Documentation

_O_n_i_o_n_s _d_a_t_a

_D_e_s_c_r_i_p_t_i_o_n:

     The 'onions' data frame contains 84 sets of observations from an
     experiment involving the production of white Spanish onions in two
     South Australian locations.

_U_s_a_g_e:

     data(onions)

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _d_e_n_s areal density of plants (plants per square metre)

     _y_i_e_l_d onion yield (grammes per plant).

     _l_o_c_a_t_i_o_n indicator of location: 0=Purnong Landing, 1=Virginia.

_S_o_u_r_c_e:

     Ratkowsky, D. A. (1983). _Nonlinear Regression Modeling: A Unified
     Practical Approach._ New York: Marcel Dekker.

_R_e_f_e_r_e_n_c_e_s:

     Ruppert, D., Wand, M.P. and Carroll, R.J. (2003)
      _Semiparametric Regression_ Cambridge University Press.
      <URL: http://stat.tamu.edu/~carroll/semiregbook/>

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

     library(SemiPar)
     data(onions)
     attach(onions)
     points.cols <- c("red","blue")
     plot(dens,yield,col=points.cols[location+1],pch=16)
     legend(100,250,c("Purnong Landing","Virginia"),col=points.cols,pch=rep(16,2))

