snails                 package:MASS                 R Documentation

_S_n_a_i_l _M_o_r_t_a_l_i_t_y _D_a_t_a

_D_e_s_c_r_i_p_t_i_o_n:

     Groups of 20 snails were held for periods of 1, 2, 3 or 4 weeks in
     carefully controlled conditions of temperature and relative
     humidity.  There were two species of snail, A and B, and the
     experiment was designed as a 4 by 3 by 4 by 2 completely
     randomized design.  At the end of the exposure time the snails
     were tested to see if they had survived; the process itself is
     fatal for the animals.  The object of the exercise was to model
     the probability of survival in terms of the stimulus variables,
     and in particular to test for differences between species.

     The data are unusual in that in most cases fatalities during the
     experiment were fairly small.

_U_s_a_g_e:

     data(snails)

_F_o_r_m_a_t:

     The data frame contains the following components:

     '_S_p_e_c_i_e_s' Snail species A (1) or B (2)

     '_E_x_p_o_s_u_r_e' Exposure in weeks

     '_R_e_l._H_u_m' Relative humidity (4 levels)

     '_T_e_m_p' Temperature, in degrees Celsius (3 levels)

     '_D_e_a_t_h_s' Number of deaths

     '_N' Number of snails exposed

_S_o_u_r_c_e:

     Zoology Department, The University of Adelaide.

_R_e_f_e_r_e_n_c_e_s:

     Venables, W. N. and Ripley, B. D. (1999) _Modern Applied
     Statistics with S-PLUS._ Third Edition. Springer.

