Random Forest

Michael Minn - 16 April 2015

> model

Call:
 randomForest(formula = NDVI ~ ., data = database[, rfields],      na.action = na.omit) 
               Type of random forest: regression
                     Number of trees: 500
No. of variables tried at each split: 4

          Mean of squared residuals: 0.2130862
                    % Var explained: 78.88


> summary(model)
                Length Class  Mode     
call                 4 -none- call     
type                 1 -none- character
predicted       301211 -none- numeric  
mse                500 -none- numeric  
rsq                500 -none- numeric  
oob.times       301211 -none- numeric  
importance          12 -none- numeric  
importanceSD         0 -none- NULL     
localImportance      0 -none- NULL     
proximity            0 -none- NULL     
ntree                1 -none- numeric  
mtry                 1 -none- numeric  
forest              11 -none- list     
coefs                0 -none- NULL     
y               301211 -none- numeric  
test                 0 -none- NULL     
inbag                0 -none- NULL     
terms                3 terms  call     
na.action       152170 omit   numeric  


> importance(model)
             IncNodePurity
SQMLAND          22156.939
SQMWATER          8838.317
MEDIANAGE        24688.405
MEDHHINC         26790.211
MEANHHSIZE       23293.283
PCOWNEROCC       13776.804
PCTURNOVER       13744.089
PCBORNUSA        13494.287
PCUNEMPLOYED      9865.677
SQMLAWN          31388.236
MEDCONSTYR       54570.323
PMINPET          12390.099

Variables

Landsat Data

NDVI: Median tract residential area NDVI

Census Data

2000 Decennial census, 2009-2013 American Community Survey

SQMLAND: Tract area in square meters

SQMWATER: Tract area covered in water in square meters

MEDIANAGE: Median age

MEDHHINC: Median household income

MEANHHSIZE: Mean number of members in each household

PCOWNEROCC: Percent housing units owner-occupied

PCTURNOVER: Percent residents in same house one year ago

PCBORNUSA: Percent of residents born in the USA

PCUNEMPLOYED: Percent 16 years of age or older unemployed (mean?)

Parcel Data

Data from 2013 Maricopa County Assessor's Office ST 42030 File

SQMLAWN: Total square meters of PLA (lot_size - (home_size / floors) - pool_size)

MEDCONSTYR: Median construction year

Climate Data

PMINPET: Precipitation - potential evapotranspiration