Smoking                 package:cmm                 R Documentation

_S_m_o_k_i_n_g _c_e_s_s_a_t_i_o_n _a_f_t_e_r _e_x_p_e_r_i_m_e_n_t_a_l _i_n_t_e_r_v_e_n_t_i_o_n

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

     Data from an experiment designed for the investigation of the
     effectiveness of a particular expert system intervention to
     convince people to quit smoking. N = 4,144 subjects were randomly
     assigned to either the control (assessment only) or the
     experimental condition (TTM intervention). Information was
     collected on their smoking habits and their attitudes towards
     smoking at the start of the study, at the sixth, twelfth,
     eighteenth, and twenty-fourth month. For more detailed information
     see Bergsma et al. (2009) and Prochaska et al. (2001).

     The data are tabulated in Bergsma, Croon, and Hagenaars (2009,
     Tables 5.11 to 5.14).

     Section 5.2.3 in Bergsma, Croon and Hagenaars (2009).

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

     data(Smoking)

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

     A data frame with 4144 observations on the following variables.

     '_G_r_o_u_p' (factor): 1 = TTM intervention; 2 = Assessment only.

     '_s_m_s_t_0_0' Behavior at beginning (ordered): 1 = Precontemplation; 2
          = Contemplation; 3 = Preparation; 4 = Action; 5 =
          Maintenance.

     '_s_m_s_t_0_6' Behavior after 6 months (ordered): see 'smst00'

     '_s_m_s_t_1_2' Behavior after 12 months (ordered): see 'smst00'

     '_s_m_s_t_1_8' Behavior after 18 months (ordered): see 'smst00'

     '_s_m_s_t_2_4' Behavior after 24 months (ordered): see 'smst00'

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

     Cancer Prevention Research Center, Univisity of Rhode Island, US.
     See Prochaska, Velicer, Fave, Rossi & Tosh (2001).

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

     Examples in book: <URL:
     http://stats.lse.ac.uk/bergsma/cmm/R%20files/Smoking.R>

     Bergsma, W. P., Croon, M. A., & Hagenaars, J. A. P. (2009).
     _Marginal models for dependent, clustered, and longitudinal
     categorical data._ New York: Springer.

     Prochaska, J. O., Velicer, W. F., Fava, J. L. Rossi, J. S., &
     Tosh, J. Y. (2001). Evaluating a population-based recruitment
     approach and a stage-based expert system intervention for smoking
     cessation. _Addictive Behaviors, 26_, 583-602.

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

     ####################################################################################
     # Read data
     data(Smoking)
     dat <- Smoking

     ####################################################################################
     # Table TXBR

     # matrix producing 4x2x3x6 table TXBR
     atTXBR = MarginalMatrix(c("X","B","R1","R2","R3","R4"), list(c("X","B","R1"), c("X","B","R2"), c("X","B","R3"), c("X","B","R4")), c(2, 3, 5, 5, 5, 5));
     bt  = ConstraintMatrix(c("T","X","B","R"), list(c("T","X","B"), c("R")), c(4, 2, 3, 5))
     model = list(bt,"log", atTXBR)

     fit=MarginalModelFit(dat, model, MaxStepSize =.3, MaxSteps=100, ShowProgress=5)

