labor data frame has 358 rows and 4 columns of the
change in pain over time for several 83 women in labor.
This data frame contains the following columns:
an ordered factor indicating the subject on which the
measurement was made. The levels are labelled
a numeric vector of self–reported pain scores on a 100mm line.
a dummy variable with values
1 for subjects who received a pain medication and
0 for subjects who received a placebo.
a numeric vector of times (minutes since randomization) at which
pain was measured.
The labor pain data were reported by Davis (1991) and successively analyzed by Jung (1996) and Geraci and Bottai (2007). The data set consists of repeated measurements of self–reported amount of pain on N = 83 women in labor, of which 43 were randomly assigned to a pain medication group and 40 to a placebo group. The response was measured every 30 min on a 100–mm line, where 0 means no pain and 100 means extreme pain. A nearly monotone pattern of missing data was found for the response variable and the maximum number of measurements for each woman was six.
Davis CS (1991). Semi–parametric and non–parametric methods for the analysis of repeated measurements with applications to clinical trials. Statistics in Medicine 10, 1959–80.
Geraci M and Bottai M (2007). Quantile regression for longitudinal data using the asymmetric Laplace distribution. Biostatistics 8(1), 140–154.
Jung S (1996). Quasi–likelihood for median regression models. Journal of the American Statistical Association 91, 251–7.