Informal descriptive label for a Moran's I value

Explicit warning: this is a descriptive convention specific to this package, not a recognised disciplinary standard – there is no universal, citable threshold for Moran's I magnitude (it depends on the weight matrix used). Use only as an informal aid, never as citable justification in a formal write-up. method = "moran" results only – Getis-Ord General G's natural range and expected value under H0 differ enough from Moran's I that these same thresholds would not transfer meaningfully (see ?spatial_autocorrelation's "Limitations" section).

Usage

classify_moran(I)

Arguments

I

Numeric. A Moran's I value (e.g. result$statistic from a method = "moran" result).

Value

Invisibly, a character label ("low", "moderate", or "strong").

Details

Function type: Reporting/derived function – summarises or plots the output of another function; it does not compute any new statistic. Not exported – folded into print()/summary() of a "spatial_autocorrelation" object (see ?print.sptrends), the category now shown there for every method = "moran" spatial_autocorrelation() result automatically, without a separate call.

References

• Moran, P.A.P. (1950) Notes on Continuous Stochastic Phenomena. Biometrika, 37(1-2), 17-23. doi:10.1093/biomet/37.1-2.17

See also

Other Spatial autocorrelation diagnostic functions: spatial_autocorrelation(), spatial_autocorrelation_null_plot(), spatial_autocorrelation_summary()

Examples

# A moderately positive Moran's I would be labelled by this
# function's own convention as follows (see the "Warning" message it
# prints about that label not being a disciplinary standard) --
# called internally wherever a categorical Moran's I label is
# shown, e.g. spatial_autocorrelation()'s own summary output:
# classify_moran(0.32)