backPain.RdData from a study of patients suffering from back pain. Prognostic variables were recorded at presentation and progress was categorised three weeks after treatment.
data(backPain)A data frame with 101 observations on the following 4 variables.
length of previous attack.
pain change.
lordosis.
an ordered factor describing the progress of each
patient with levels worse < same <
slight.improvement < moderate.improvement <
marked.improvement < complete.relief.
http://ideas.repec.org/c/boc/bocode/s419001.html
The data set and this help file was copied from gnm so that a vignette in VGAM could be run; the analysis is described in Yee (2010).
The data frame backPain2 is a modification of
backPain where the variables have been renamed
(x1 becomes x2,
x2 becomes x3,
x3 becomes x4)
and
converted into factors.
Anderson, J. A. (1984). Regression and Ordered Categorical Variables. J. R. Statist. Soc. B, 46(1), 1-30.
Yee, T. W. (2010). The VGAM package for categorical data analysis. Journal of Statistical Software, 32, 1–34. doi:10.18637/jss.v032.i10 .
summary(backPain)
#> x1 x2 x3 pain
#> Min. :1.000 Min. :1.000 Min. :1.000 worse : 5
#> 1st Qu.:1.000 1st Qu.:2.000 1st Qu.:1.000 same :14
#> Median :2.000 Median :2.000 Median :1.000 slight.improvement :18
#> Mean :1.614 Mean :2.069 Mean :1.366 moderate.improvement:20
#> 3rd Qu.:2.000 3rd Qu.:3.000 3rd Qu.:2.000 marked.improvement :28
#> Max. :2.000 Max. :3.000 Max. :2.000 complete.relief :16
summary(backPain2)
#> x2 x3 x4 pain
#> 1:39 1:21 1:64 worse : 5
#> 2:62 2:52 2:37 same :14
#> 3:28 slight.improvement :18
#> moderate.improvement:20
#> marked.improvement :28
#> complete.relief :16