veneer {WWGbook}R Documentation

veneer data in Chapter 7

Description

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).

Usage

data(veneer)

Format

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

patient
: Patient ID variable (Level 3 ID)
tooth
: Tooth number (Level 2 ID)
age
: Age of patient when veneer was placed, constant for all observations on the same patient
base.gcf
: Baseline measure of Gingival Crevicular Fluid for the tooth, constant for all observations on the same tooth
cda
: Average contour difference in the tooth after veneer placement, constant for all observations on the same tooth
time
: Time points of longitudinal measures (3 = Three Months, 6 = Six Months)
gcf
: Gingival Crevicular Fluid adjacent to the tooth, collected at each time point (Dependent Variable)

References

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.

Examples

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)) 


[Package WWGbook version 1.0.0 Index]