R help - Mar 2010 - trouble getting multinimial logit model to work properly

Greetings all, 
please consider the following data:
#Build Data frame
Slope<-c(1.291370, 12.208500,  2.110930,  0.578990,  5.019520,  0.807444, 
0.554079
, 1.257080,  0.241504 , 0.184337 , 0.383044 , 0.342021)
Exposure<-c(790.54,  1167.79 ,  845.58 , 1082.47 , 1189.61 ,  677.17 ,
2058.56 ,  469.09
,   112.02 ,  803.31 ,  254.14  ,1336.16)
FwyDist<-c(11809.4222 ,10623.0458, 12279.6271, 11571.2744, 15400.9318, 
7786.4093,  1173.0635
 , 2630.1493 , 4408.2271  ,6333.0374  ,8070.0090,   751.3506)
RTotEmp<-c( 2707.4835  ,     0.0000     ,729.5191  , 15652.1514  
,25613.8658  , 74214.9622
, 15094.1017,    1682.1790 ,  15742.1817    ,   0.0000,  257715.0631  ,
13564.0576)
RTotHh<-c( 38643.1731 , 17361.7998 , 96782.8727 , 57936.3218 , 42770.3231 ,
32393.5014
,40490.5267 , 32682.3341 , 17151.9293 , 35989.6510 ,167356.2668 
,63072.8678)
SFsubM<-c(0,1,1,0,0,0,0,0,0,1,0,0)
TestData<-data.frame(Slope,Exposure,FwyDist,RTotEmp,RTotHh,SFsubM)

#Run Model
z.out <- zelig(SFsubM ~ Slope + IntDist + Exposure  + RTotEmp + RTotHh, 
     model="mlogit", data=TestData)

I get the error 
Error in attr(tt, "depFactors")$depFactorVar : 
  $ operator is invalid for atomic vectors

Which i dont know what it means.  The data is a subset of my real data but
should reflect what im trying to do.  Thanks

JR
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JR,

You need to use as.factor() for the DV (even if it is already a factor).
Also, your formula includes a variable not in your sample data,
"IntDist",
perhaps you meant "FwyDist"?

Try:

zelig(as.factor(SFsubM) ~ Slope + Exposure + FwyDist + RTotEmp + RTotHh,
model="mlogit", data=TestData)
Also, see http://gking.harvard.edu/zelig/docs/mlogit.pdf for more details on
using the mlogit model.

Best regards,


Josh
On Wed, Mar 10, 2010 at 1:23 PM, LCOG1 <jroll@lcog.org> wrote:
>
>
> #Run Model
> z.out <- zelig(SFsubM ~ Slope + IntDist + Exposure  + RTotEmp + RTotHh,
>     model="mlogit", data=TestData)
>
> I get the error
> Error in attr(tt, "depFactors")$depFactorVar :
>  $ operator is invalid for atomic vectors
>
> Which i dont know what it means.  The data is a subset of my real data but
> should reflect what im trying to do.  Thanks
>

-- 
Joshua Wiley
Senior in Psychology
University of California, Riverside
http://www.joshuawiley.com/

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