# calculates overall difference at the category level from a square contingency table

### Description

calculates overall difference at the category level from a contingency table derived from the crosstabulation between a comparison variable (or variable at time *t*), and a reference variable (or variable at time *t*+1). Overall difference is equivalent to the addition of the quantity and allocation components of difference (i.e., overall difference can be disaggregated into quantity and allocation components).

### Usage

1 | ```
overallDiffCatj(ctmatrix)
``` |

### Arguments

`ctmatrix` |
matrix representing a square contingency table between a comparison variable (rows) and a reference variable (columns) |

### Value

a numeric vector containing overall difference between the comparison variable and the reference variable at the category level. Output values are given in the same units as `ctmatrix`

### References

Pontius Jr., R.G., Millones, M. 2011. *Death to Kappa: birth of quantity disagreement and allocation disagreement for accuracy assessment*. International Journal of Remote Sensing 32 (15), 4407-4429.

Pontius Jr., R.G., Santacruz, A. 2014. *Quantity, exchange and shift components of difference in a square contingency table*. International Journal of Remote Sensing 35 (21), 7543-7554.

### See Also

`overallDiff`

### Examples

1 2 3 4 | ```
comp <- raster(system.file("external/comparison.rst", package="diffeR"))
ref <- raster(system.file("external/reference.rst", package="diffeR"))
ctmatCompRef <- crosstabm(comp, ref)
overallDiffCatj(ctmatCompRef)
``` |