toxicity             package:robustbase             R Documentation

_T_o_x_i_c_i_t_y _o_f _C_a_r_b_o_x_y_l_i_c _A_c_i_d_s _D_a_t_a

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

     The aim of the experiment was to predict the toxicity of
     carboxylic acids on the basis of several molecular descriptors.

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

     data(toxicity)

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

     A data frame with 38 observations on the following 10 variables
     which are attributes for carboxylic acids:

     '_t_o_x_i_c_i_t_y' aquatic toxicity, defined as log(IGC50^(-1)); typically
          the "response".

     '_l_o_g_K_o_w' log Kow, the partition coefficient

     '_p_K_a' pKa: the dissociation constant

     '_E_L_U_M_O' *E*nergy of the *l*owest *u*noccupied *m*olecular
          *o*rbital

     '_E_c_a_r_b' Electrotopological state of the *carb*oxylic group

     '_E_m_e_t' Electrotopological state of the *met*hyl group

     '_R_M' Molar refractivity

     '_I_R' Refraction index

     '_T_s' Surface tension

     '_P' Polarizability

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

     The website accompanying the MMY-book: <URL:
     http://www.wiley.com/legacy/wileychi/robust_statistics>

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

     Maguna, F.P., N\'u\~nez, M.B., Okulik, N.B. and Castro, E.A.
     (2003) Improved QSAR analysis of the toxicity of aliphatic
     carboxylic acids; _Russian Journal of General Chemistry_ *73*,
     1792-1798.

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

     data(toxicity)
     summary(toxicity)
     plot(toxicity)
     plot(toxicity ~ pKa, data = toxicity)

     ## robustly scale the data (to scale 1) using Qn
     (scQ.tox <- sapply(toxicity, Qn))
     scTox <- scale(toxicity, center = FALSE, scale = scQ.tox)
     csT <- covOGK(scTox, n.iter = 2,
                   sigmamu = s_Qn, weight.fn = hard.rejection)
     as.dist(round(cov2cor(csT$cov), 2))

