An agreement plot shows the agreement between two binary or semi-quantitiatve
Bangdiwala (2013) devised the agreement plot as a complement to the kappa or
B-statistics. It is invaluable for assessing agreement as it gives a visual impression that no
summary statistic can convey.
The agreement plot is a visual representation of a k by k square contingency table. Each
black rectangle represents the marginal totals of the rows and columns. Shaded boxes represent
the agreement based on the diagonal cell frequencies; they are positioned inside the
rectangles using the sum of the off-diagonal cell frequencies from the same row and column.
The partial agreement in the off-diagonal cells can be represented similarly with decreased
shading based on the distance from the diagonal. The visualization is affected by the order of
the categories, and so the plot is only useful for ordinal or binary data. The plot can have
the origin at the bottom-left corner, or at the top-left where it more clearly mimics the
Perfect agreement is represented by rectangles that are all perfect squares, with corners on
the diagonal identity line, and with shaded boxes equal to the rectangle. Lesser agreement is
represented by the area of shaded boxes compared to the area of rectangles. The path of the
rectangles, how they deviate from the 45-degree identity line, represents bias in the marginal