veneer                package:WWGbook                R Documentation

_v_e_n_e_e_r _d_a_t_a _i_n _C_h_a_p_t_e_r _7

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

     The Dental Veneer data were collected by researchers at the
     University of Michigan Dental School, in a study investigating the
     impact of veneer placement on subsequent gingival (gum) health
     among adult patients (Ocampo, 2005).

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

     data(veneer)

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

     A data frame with 110 observations on the following 7 variables.

     _p_a_t_i_e_n_t : Patient ID variable (Level 3 ID)

     _t_o_o_t_h : Tooth number (Level 2 ID)

     _a_g_e : Age of patient when veneer was placed, constant for all
          observations on the same patient

     _b_a_s_e._g_c_f : Baseline measure of Gingival Crevicular Fluid for the
          tooth, constant for all observations on the same tooth

     _c_d_a : Average contour difference in the tooth after veneer
          placement, constant for all observations on the same tooth

     _t_i_m_e : Time points of longitudinal measures (3 = Three Months, 6 =
          Six Months)

     _g_c_f : Gingival Crevicular Fluid adjacent to the tooth, collected
          at each time point (Dependent Variable)

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

     Ocampo, J., Data taken from M.S. Thesis, Effect of Porcelain
     Laminate Contour on Gingival Inflammation, University of Michigan
     School of Dentistry, 2005

     West, B., Welch, K. & Galecki, A, Linear Mixed Models: A Practical
     Guide Using Statistical Software, Chapman Hall / CRC Press, first
     edition, 2006.

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

     attach(veneer)

     #### Figure 7.2: Raw GCF values for each tooth vs. time, by patient. Panels are ordered by patient age.
     age.f <- factor(age)
     time.f <- factor(time)
     tooth.f <- factor(tooth)

     veneer <- data.frame(veneer,age.f, time.f, tooth.f)
     sort(age.f)

     library(lattice)  # Load the library for trellis graphics.

     # Load the nlme library, which is required for the 
     # plots below as well as for subsequent models.
     library(nlme)

     veneer.g1 <- groupedData(gcf ~ time | tooth.f, 
     outer = ~ age.f, data = veneer)
     plot(veneer.g1, display = "tooth", outer = TRUE, aspect = 2, key = FALSE, xlab = "time", ylab = "GCF", main="Panels are ordered by patient age." ,layout=c(4,3)) 

