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BMC Med Res Methodol. 2013 Jul 29;13:97. doi: 10.1186/1471-2288-13-97.

The agreement chart.

Author information

1
Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA. kant@unc.edu

Abstract

BACKGROUND:

When assessing the concordance between two methods of measurement of ordinal categorical data, summary measures such as Cohen's (1960) kappa or Bangdiwala's (1985) B-statistic are used. However, a picture conveys more information than a single summary measure.

METHODS:

We describe how to construct and interpret Bangdiwala's (1985) agreement chart and illustrate its use in visually assessing concordance in several example clinical applications.

RESULTS:

The agreement charts provide a visual impression that no summary statistic can convey, and summary statistics reduce the information to a single characteristic of the data. However, the visual impression is personal and subjective, and not usually reproducible from one reader to another.

CONCLUSIONS:

The agreement chart should be used to complement the summary kappa or B-statistics, not to replace them. The graphs can be very helpful to researchers as an early step to understand relationships in their data when assessing concordance.

PMID:
23890315
PMCID:
PMC3733724
DOI:
10.1186/1471-2288-13-97
[Indexed for MEDLINE]
Free PMC Article

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