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N1PLOT procedure

Displays summaries of data from a set of n-of-1 trials (S.J. Senn & R.W. Payne).

Options

PRINT = string token Controls printed output (differences); default diff
PLOT = string tokens Types of standard errors to be printed with the means (alldifferences, differencesbysubject, alloutcomes, outcomesbysubject); default alld, diff, allo, outc

Parameters

Y = variates Each of these contains the data values for an analysis
TREATMENTS = factors Treatment factor for each analysis
SUBJECTS = factors Subject factor for each analysis
CYCLES = factors Cycles factor for each analysis

Description

An n-of-1 trial is a medical trial in a single subject to compare two treatments. The design consists of “cycles” of pairs of periods to which the treatments are allocated in one of the two possible orders. In a set of n-of-1 trials, several subjects (or patients) receive cycles of treatments over a sequence of periods.

The Y parameter supplies a variate containing the results of the set of trials. The TREATMENTS parameter supplies a factor specifying the treatment allocations. The SUBJECTS parameter supplies a factor to specify the subjects, and the CYCLES parameter supplies a factor to specify the cycles within each subject

By default N1PLOT prints the results for the two treatments, and their difference, within each cycle, but you can set option PRINT=* to suppress this.

The PLOT option controls the plots that are produced, with the following settings:

alldifferences dot histogram in window 3 containing (all the) differences;
differencesbysubjecttrellis plot showing the difference in outcomes in the cycles for each subject;
alloutcomesgraph in window 3 plotting all the outcomes for the second treatment against those for the first treatment; and
outcomesbysubjecttrellis plot plotting outcomes for the second treatment against those for the first treatment for each subject.
 
Acknowledgements: this research was started when working on the European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement no. 602552 for the IDEAL project and completed when working on the National Institute for Health and Care Research (NIHR) DIAMOND project. Support from both is gratefully acknowledged as is collaboration with Artur Araujo, Robin Chatters, Andrew Cooke, Liv Hawksworth, Steven Julious and Sonia Leite.

 

Options: PRINT, PLOT.

Parameters: Y, TREATMENTS, SUBJECTS, CYCLES.

See also

Procedures: N1ANOVA, N1DESIGN, N1SIMULATE, N1TEST

GenStat Reference Manual 1 Summary section on: Graphics

Example

CAPTION   'N1PLOT example'; STYLE=meta
" Simulated data for a series of n-of-1 trials in asthma for which
  two bronchodilators, A and B are given in a single dose with each
  period of treatment well separated by washout.Forced expiratory volume
  in one second (FEV1) has been measure in mL 12 hours after treatments.
  Twelve patients have each been treated in three cycles. "
SPLOAD     '%data%/N1asthma.gsh'
N1PLOT     [pr=*; pl=outc] FEV1; Treatments=Treatment; Subjects=Patient; Cycles=Cycle
Updated on April 15, 2024

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