oats                  package:MASS                  R Documentation

_D_a_t_a _f_r_o_m _a_n _O_a_t_s _F_i_e_l_d _T_r_i_a_l

_D_e_s_c_r_i_p_t_i_o_n:

     The yield of oats from a split-plot field trial using three
     varieties and four levels of manurial treatment.  The experiment
     was laid out in 6 blocks of 3 main plots, each split into 4
     sub-plots.  The varieties were applied to the main plots and the
     manurial treatments to the sub-plots.

_U_s_a_g_e:

     oats

_F_o_r_m_a_t:

     This data frame contains the following columns:

     '_B' Blocks, levels I, II, III, IV, V and VI.

     '_V' Varieties, 3 levels.

     '_N' Nitrogen (manurial) treatment, levels  0.0cwt, 0.2cwt, 0.4cwt
          and 0.6cwt, showing the application in cwt/acre.

     '_Y' Yields in 1/4lbs per sub-plot, each of area 1/80 acre.


_S_o_u_r_c_e:

     Yates, F. (1935) Complex experiments, _Journal of the Royal
     Statistical Society Suppl._ *2*, 181-247.

     Also given in Yates, F. (1970) _Experimental design: Selected
     papers of Frank Yates, C.B.E, F.R.S._ London: Griffin.

_R_e_f_e_r_e_n_c_e_s:

     Venables, W. N. and Ripley, B. D. (2002) _Modern Applied
     Statistics with S._ Fourth edition.  Springer.

_E_x_a_m_p_l_e_s:

     oats$Nf <- ordered(oats$N, levels = sort(levels(oats$N)))
     oats.aov <- aov(Y ~ Nf*V + Error(B/V), data = oats, qr = TRUE)
     summary(oats.aov)
     summary(oats.aov, split = list(Nf=list(L=1, Dev=2:3)))
     par(mfrow = c(1,2), pty = "s")
     plot(fitted(oats.aov[[4]]), studres(oats.aov[[4]]))
     abline(h = 0, lty = 2)
     oats.pr <- proj(oats.aov)
     qqnorm(oats.pr[[4]][,"Residuals"], ylab = "Stratum 4 residuals")
     qqline(oats.pr[[4]][,"Residuals"])

     par(mfrow = c(1,1), pty = "m")
     oats.aov2 <- aov(Y ~ N + V + Error(B/V), data = oats, qr = TRUE)
     model.tables(oats.aov2, type = "means", se = TRUE)