breath               package:Fahrmeir               R Documentation

_B_r_e_a_t_h_i_n_g _T_e_s_t

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

     Effects of age and smoking status on breathing test results for 
     workers in industrial plants in  Texas.

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

     data(breath)

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

     A data frame with 18 observations on the following 4 variables.

     _A_g_e a factor with levels '<40' '40-59'

     _n number of workers in group

     _S_m_o_k_i_n_g._s_t_a_t_u_s a factor with levels 'Current.smoker' 
          'Former.smoker' 'Never.smoked'

     _B_r_e_a_t_h_i_n_g._t_e_s_t a factor with levels 'Abnormal'  'Borderline'
          'Normal'

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

     We consider the effects of age and smoking status upon breathing
     test results for workers in industrial plants in Texas.  The test
     results are given on an ordered scale with categories "Abnormal",
     "Borderline" and "Normal". It is of interest how age and smoking
     status are connected to breathing test results.

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

     Ludwig Fahrmeir, Gerhard Tutz (1994):  Multivariate Statistical
     Modelling Based on Generalized Linear Models. Springer Series in
     Statistics.  Springer Verlag. New-York  Berlin Heidelberg

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

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

     str(breath)
     breath$Breathing.test <- ordered(breath$Breathing.test)
     library(MASS)
     breath.polr1 <- polr(Breathing.test ~ Age*Smoking.status, weight=n, 
                          data=breath)
     breath.polr2 <- polr(Breathing.test ~ Age*Smoking.status, weight=n, 
                          data=breath, method="cloglog")
     summary(breath.polr1)
     summary(breath.polr2)
     # continuation ratio models (as of page 89) might be fitted with
     # Design or VGAM package.

