The data is obtained from a trial in which chronically ill mental health patients were randomized across two treatments: placebo and an active drug. A questionnaire instrument was used to assess each patient's mental state at weeks 0, 1, 2, 4, 6 and 8 post-randomisation, a high recorded score implying a severe condition. Some of the 100 patients dropped out of the study for reasons that were thought to be related to their mental state, and therefore potentially informative; others dropped out for reasons unrelated to their mental state.
data(mental)
A balanced data set with respect to the times at which observations recorded. The data consists of the following variables on each patient:
id
integer: patient identifier.
Y.t0
integer: mental state assessment in week 0. Coded
NA
if missing.
Y.t1
integer: mental state assessment in week 1. Coded
NA
if missing.
Y.t2
integer: mental state assessment in week 2. Coded
NA
if missing.
Y.t4
integer: mental state assessment in week 4. Coded
NA
if missing.
Y.t6
integer: mental state assessment in week 6. Coded
NA
if missing.
Y.t8
integer: mental state assessment in week 8. Coded
NA
if missing.
treat
integer: treatment allocation. Coded as 0 =
placebo; 1 =
active drug.
n.obs
integer: number of non-missing mental state assessments.
surv.time
numeric: imputed dropout time in weeks. Coded as
surv.time = 8.002
for completers.
cens.ind
integer: censoring indicator. Coded as 0 =
completer or non-informative dropout; 1 =
potentially informative
dropout.
Henderson R, Diggle PJ, Dobson A. Joint modelling of longitudinal measurements and event time data. Biostatistics. 2000; 1(4): 465-480.
Diggle PJ, Farewell D, Henderson R. Longitudinal data with dropout: objectives, assumptions and a proposal (with Discussion). Applied Statistics. 2007; 56: 499-550.
heart.valve
, liver
,
epileptic
.