This vignette discusses the consistency of results between the basic
geographic detector in the gdverse package and existing R
packages of GDModels (i.e., geodetector and GD
packages). Use the CollectData data from
geodetector package as the demo;
collectdata = geodetector::CollectData
res1 = geodetector::factor_detector("incidence",
c("soiltype","watershed","elevation"),
collectdata)
res1
## [[1]]
## q-statistic p-value
## soiltype 0.3857168 0.3632363
##
## [[2]]
## q-statistic p-value
## watershed 0.6377737 0.0001169914
##
## [[3]]
## q-statistic p-value
## elevation 0.6067087 0.04080407
res2 = GD::gd(incidence ~ ., data = collectdata)
res2
## variable qv sig
## 1 watershed 0.6377737 0.000128803
## 2 soiltype 0.3857168 0.372145486
## 3 elevation 0.6067087 0.043382244
res3 = gdverse::geodetector(incidence ~ ., data = collectdata)
res3
## Factor Detector
##
## | variable | Q-statistic | P-value |
## |:---------:|:-----------:|:-----------:|
## | watershed | 0.6377737 | 0.000128803 |
## | elevation | 0.6067087 | 0.043382244 |
## | soiltype | 0.3857168 | 0.372145486 |The q-statistic calculations for all variables in the three packages
are consistent, but there are slight differences in the results of the
q-values. Among them, gdverse is consistent with the
GD package, and there are differences with the
geodetector package. This is caused by the inconsistent
choice of the non-central F-distribution parameters of the p-value for
the q-statistic; when there is only one sample in a certain
stratification, it cannot calculate the variance and therefore does not
contribute to the q-statistic calculation. The gdverse and
GD packages use the same strategy, which is to directly
remove these single-sample layers, but the geodetector
package calculates the total sample size and stratification number
directly before data processing, so it causes a slight difference in the
estimation of the p-value for the q-statistic. In actual problems, this
situation occurs less frequently. We believe that using the actual
number of samples and stratifications participating in the calculation
is more prudent, so we chose the same processing strategy as the
GD package.