sitka                package:SemiPar                R Documentation

_S_i_t_k_a _s_p_r_u_c_e _d_a_t_a

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

     The 'sitka' data frame contains measurements of log-size for 79
     Sitka spruce trees grown in normal or ozone-enriched environments.
     Within each year, the data are organised in four blocks,
     corresponding to four controlled environment chambers. The first
     two chambers, containing 27 trees each, have an ozone-enriched
     atmosphere, the remaining two, containing 12 and 13 trees
     respectively, have a normal (control) atmosphere.

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

     data(sitka)

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

     This data frame contains the following columns:

     _i_d._n_u_m identification number of tree.

     _o_r_d_e_r time order ranking within each tree.

     _d_a_y_s time in days since 1st January, 1988.

     _l_o_g._s_i_z_e tree size measured on a logarithmic scale.

     _o_z_o_n_e indicator ozone treatment: 0=control,1=ozone.

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

     Diggle, P.J., Heagerty, P., Liang, K.-Y. and Zeger, S.L. (2002).
     _Analysis of Longitudinal Data, Second Edition_, Oxord: Oxford
     University Press.

_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(sitka)
     attach(sitka)
     library(lattice)
     ozone.char <- rep("control",nrow(sitka))
     ozone.char[ozone==1] <- "ozone"
     xyplot(log.size~days|ozone.char,data=sitka,groups=id.num,type="b")

