[R] Can't understand error message :-{

[Peter Dalgaard BSA]

Stuart Luppescu <s-luppescu at uchicago.edu> writes:

> attach(sizef)
> mschmod <- lm (mavgres ~ crimesch + socstat + povnojob + ploinc94 + aa94 +
> hisp94 + minty94 + mixed94, data=sizef)
> plot(mschmod$residuals ~ size94)
> 
> The last line gives this error message:
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames,  : variable lengths differ
> 
> In fact, the lengths are different:
> > length(mschmod$residuals)
> [1] 379
> > length(size94)
> [1] 384
> 
> but I'm sure I don't know 1) how this happened since it all came from the same
> data frame, or 2) why it should prevent me from plotting the data. If someone
> can tell me how to fix this (before I have to present the results at this
> Thursday's meeting!) I'd be very appreciative. 

(1) Missing values in response and/or regressors cause cases to be
    discarded. 
(2) Plotting which of the y's against which x's ?

plot(mschmod$residuals ~ size94[complete.cases(mavgres,crimesch,
socstat,povnojob,ploinc94,aa94,hisp94,minty94,mixed94)])

should do the trick. Or, simpler but sneakier:

attach(sizef[rownames(mschmod$model),])
plot(residuals(mschmod) ~ size94)
detach()

It should also work with:

evalq(plot(residuals(mschmod) ~ size94), sizef[rownames(mschmod$model),])

(none of the above is tested, since I don't have your data of course)
-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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