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OBUMRM
A
FORTRAN Program to Analyze Multi-Reader, Multi-Modality ROC
Data Statistical Method described in:
Obuchowski NA, Rockette HE. Hypothesis testing of diagnostic
accuracy for multiple readers and multiple tests: an ANOVA
approach with dependent observations. Communications in
Statistics - Simulations 1995; 24: 285-308.
Obuchowski NA. Multireader, multimodality receiver operating
characteristic curve studies: hypothesis testing and sample
size estimation using an analysis of variance approach with
dependent observations. Academic Radiology 1995; 2: S22-S29.
Software
written by Nancy A. Obuchowski, Ph.D., The Cleveland Clinic
Foundation
Purpose:
To perform the computations of the Obuchowski-Rockette statistical
method for multireader, multimodality ROC datasets. The inputted
dataset should have the following specifications: N subjects
without the condition ("normals") and M subjects
with the condition ("diseased") each underwent I
diagnostic tests. The results of the I diagnostic tests were
interpreted by the same sample of J readers. The objective
of the study is to compare the mean accuracies of readers
in the I tests to determine if the accuracy of the I tests
differ.
Notes:
- We
assume there is a gold standard that provides each patients'
true diagnosis, i.e. distinguishes normal from abnormal
patients without error.
- We
assume that the readers interpreted the test results blinded
to other test results and the gold standard result.
- We
assume there is only one test result per patient, per reader,
per diagnostic test. The following scenarios are not appropriate
for this program: analysis of the test results of the two
eyes of a patient, analysis of the test results of the two
kidneys of a patient.
- We
assume there is no missing datapoints.
- The
program can accomodate either ordinal or continuous-scale
test results.
-
Under FORMAT A, the program estimates the area under the
empirical ROC curve (so called "nonparametric estimate")
and performs the necessary calculations using these estimates
of accuracy.
***To use other estimates of the ROC area (e.g. binormal
MLEs) or to use other measures of accuracy (e.g. partial
area under the ROC curve), the data must be inputted using
FORMAT B.
- The
program treats the diagnostic tests as fixed effects, and
the patient sample and readers as random effects.
- The
program is currently dimensioned for either 2 or 3 modalities,
up to 15 readers, and up to 500 patients with and 500 without
the condition. These dimensions can be changed.
- The
current name of the input file is 'obumrm_in.dat'. The current
name of the output file is 'obumrm_out.dat'.
- There
are example input and output files that can be used as templates
for data entry and as verification that the program is performing
properly.
Files
for Downloading:
The following plain text files may be downloaded by clicking
on the filenames.
ReadMe file on OBUMRM.FOR readme.txt
Instructions for using FORMAT A instructionsA.txt
formAordin.dat: An example
input dataset in format A (ordinal-scale data)
formAcont.dat: An example
input dataset in format A (continuous-scale data)
Instructions for using FORMAT B InstructionsB.txt
formB.dat: An example input
dataset in format B
OBUMRM.FOR: The actual FORTRAN program obumrm.for
formAordin_out.dat:
The output file corresponding to formAordin.dat
formAcont_out.dat:
The output file corresponding to formAcont.dat
formB_out.dat: The output
file corresponding to formB.dat |
