Does an analysis of variance with data from a set of n-of-1 trials (S.J. Senn & R.W. Payne).
Options
PRINT = string tokens |
Controls printed output from the analysis (aovtable, information, covariates, effects, residuals, means, %cv, missingvalues); default aovt, mean |
SUBJECTINTERACTION = string token |
Whether to include the subject × treatment interaction (include, omit); default incl |
FPROBABILITY = string token |
Probabilities for variance ratios (yes, no); default no |
PSE = string tokens |
Types of standard errors to be printed with the means (differences, lsd, means, alldifferences, alllsd); default diff |
LSDLEVEL = scalar |
Significance level (%) for least significant differences; default 5 |
Parameters
Y = variates |
Each of these contains the data values for an analysis |
TREATMENTS = pointers |
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. For 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 the treatment model includes the subject-by-treatment interaction, but you can specify SUBJECTINTERACTION=omit to exclude it.
The PRINT option controls printed output, as in ANOVA. Similarly, the PSE option controls the types of standard errors to be printed with the means, the LSDLEVEL option specifies the significance level (in %) for least significant differences, and the FPROBABILITY option controls the printing of probabilities for variance ratios.
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, SUBJECTINTERACTION, FPROBABILITY, PSE, LSDLEVEL
Parameters: Y, TREATMENTS, SUBJECTS, CYCLES
See also
Procedures: N1DESIGN, N1PLOT, N1SIMULATE, N1TEST
GenStat Reference Manual 1 Summary section on: Analysis of variance.
Example
CAPTION 'N1ANOVA 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' PDESIGN [BLOCKSTRUCTURE=Patient/Cycle; TREATMENTS=Treatment,FEV1] " analysis of variance " N1ANOVA Y=Y; Subjects=Patient; Treatments=Treatment; Cycles=Cycle