I have run a linear regression with the following equation (in r):
lm(formula = logTotal ~ Continent + logArea + Method + Servs)
where Total
is $/ha/year (numeric), Area
is hectare (numeric), Continent
and Method
are factors and Servs
is numeric. It returns the output:
Call:
lm(formula = logTotal ~ Continent + logArea + Method + Servs)
Residuals:
Min 1Q Median 3Q Max
-0.99416 -0.26931 -0.00622 0.28885 1.19875
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -1.82886 0.71446 -2.560 0.016903 *
ContinentAsia 3.82452 0.60471 6.325 1.28e-06 ***
ContinentAustralasia 4.52516 0.96517 4.688 8.35e-05 ***
ContinentEurope 2.18022 0.48260 4.518 0.000130 ***
ContinentGlobal 2.44750 0.74092 3.303 0.002881 **
ContinentNorth America 2.35244 0.55281 4.255 0.000256 ***
ContinentSouth America 3.67853 0.61454 5.986 2.99e-06 ***
logArea 0.03643 0.03583 1.017 0.318911
MethodCVM -0.18171 0.43296 -0.420 0.678300
MethodOther hedonic -1.53284 0.79781 -1.921 0.066165 .
MethodValue Transfer 0.98101 0.29773 3.295 0.002941 **
Servs 0.10723 0.04273 2.509 0.018948 *
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 0.552 on 25 degrees of freedom
(65 observations deleted due to missingness)
Multiple R-squared: 0.7582, Adjusted R-squared: 0.6518
F-statistic: 7.127 on 11 and 25 DF, p-value: 2.501e-05
I wish to predict Total
based on various inputs, however I'm a bit lost on fully understanding the output. If I wished to predict "Total" on the basis of:
Continent:Global, Area:1 hectare, Method:CVM, Servs:11
is the following equation correct?
exp(Total) = 2.44750 + exp(1*0.03643) - 0.18171 + (11*0.10723)
I have read UCLA's statistics help site's FAQ on log transformed regression. I feel like I've oversimplified it but I just keep reading that link over and over and still not fully understanding. Also read How to interpret logarithmically transformed coefficients in linear regression?.