potatoes               package:sfsmisc               R Documentation

_F_i_s_h_e_r'_s _P_o_t_a_t_o _C_r_o_p _D_a_t_a

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

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

     data(potatoes)

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

     A data frame with 64 observations on the following 5 variables.

     _p_o_s a factor with levels '1:4'.

     _t_r_e_a_t a factor with 16 levels 'A' to 'H' and 'J' to 'Q', i.e.,
          'LETTERS[1:17][-9]'.

     _n_i_t_r_o_g_e_n a factor specifying the amount of nitrogen sulfate
          (NH_4), with the four levels '0,1,2,4'.

     _p_o_t_a_s_h a factor specifying the amount of potassium (K, 'kalium')
          sulfate, with the four levels '0,1,2,4'.

     _y_i_e_l_d a numeric vector giving the yield of potatoes in ...

_D_e_t_a_i_l_s:

     FIXME

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

     Bennett, J. H. (1972) _Collected Papers of R. A. Fischer_ vol.~II,
     1925-31; The University of Adelaide.

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

     T.Eden and R. A. Fisher (1929) Studies in Crop Variation. VI.
     Experiments on the Response of the Potato to Potash and Nitrogen.
     _J. Agricultural Science_ *19*, 201-213. Accessible from Bennett
     (1972), see above.

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

     data(potatoes)
     ## See the experimental design:
     with(potatoes, {
          cat("4 blocks of experiments;",
              "each does every (nitrogen,potash) combination (aka 'treat'ment) once.",
              '', sep="\n")
          print(ftable(table(nitrogen, potash, treat)))
          print(ftable(tt <- table(pos,potash,nitrogen)))
          tt[cbind(pos,potash,nitrogen)] <- as.character(treat)
          cat("The 4 blocks  pos = 1, 2, 3, 4:\n")
          ftable(tt)
          })
     ## First plot:
     with(potatoes, interaction.plot(potash,nitrogen, response=yield))

     ## ANOVAs:
     summary(aov(yield ~ nitrogen * potash + Error(pos), data = potatoes))
         # "==>" can use simply
     summary(aov(yield ~ nitrogen + potash + pos, data = potatoes))
         # and
     summary(aov(yield ~ nitrogen + potash, data = potatoes))

