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mso-paper-source:0;}div.WordSection1 {page:WordSection1;}-->Hello,Iam trying
to take the information from the summary of my best fit logisticregression
model for the occurrence of a high elevation plant spp. and createthe
appropriate equation that will calculate probability of occurrence, given
thedata. My predictors include both continuous variables (slope and a second
orderpolynomial of elevation) and a discrete variable for aspect (warm and
cool). Ihave left unchanged the default contrasts option, so I believe that
thefollowing coefficients were created using treatment contrasts. Myquestion
how can I take this summary output and create the logistic equationthat will
allow me to calculate probability of occurrence. My interests are touse this to
spatially display this info in a GIS environment. I have made adraft equation
(shown below) that uses the coefficients from this summaryoutput, but this
appears to be incorrect values always return zeroprobabilities. Presumably I
need to adjust the values in some way but I amunclear as to how to
proceed. Anyguidance would be appreciated! >summary
(model.Slope.Elevation.Aspect) Call:glm(formula= Po ~ Slope + poly(Elevation,
2) + Aspect_2, family = quasibinomial) DevianceResiduals: Min 1Q
Median 3Q Max -1.0532 -0.4167 -0.2760 -0.1823
3.3376 Coefficients: Estimate Std. Error t
valuePr(>|t|) (Intercept) -4.577707 0.222406 -20.583 < 2e-16
***Slope 0.039959 0.003593 11.121 < 2e-16
***poly(Elevation,2)1 8.050898 5.601956 1.437 0.1508
poly(Elevation,2)2 -37.694521 6.297806 -5.985 2.39e-09
***Aspect_2w 0.429229 0.174760 2.456 0.0141 * --- (1/ (1 +
exp(-1 * (-4.577707 + 0.039959*Slope + 8.050898 * poly(Elevation, 2)1 +
-37.694521 * poly(Elevation, 2)2 + 0.429229* Aspect_2w)))))
Brendan Wilson
2530 Alexis Road
Shoreacres BC
Canada V1N 4P6
Ph: 1.250.359.5905
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