[R] SEM : Warning : Could not compute QR decomposition of Hessian

[Anne Mimet]

Hi useRs,

I'm trying for the first time to use a sem. The model finally runs,  
but gives a warning saying :
"In sem.default(ram = ram, S = S, N = N, param.names = pars, var.names  
= vars,  :   Could not compute QR decomposition of Hessian.
Optimization probably did not converge. "

I found in R-help some posts on this warning, but my attemps to modify  
the code didn't change the warning message (i tried to give an error  
of 1 to the latente variables). I can't figure what the problem is.
Here is the code :


tab<-read.table("F:/Mes documents/stats/sem/donnees_corr.txt",  
header=T, sep="",na.strings = "NA")

tab[,46]<-as.factor(tab[,46])
tab[,24]<-as.factor(tab[,24])
tab[,40]<-as.factor(tab[,40])

fct_cor<-hetcor(tab, ML=T)
cor_tab<- fct_cor$correlations

moment_tab<-read.moments(diag=F, names=c('c1','c2', 'c3','c4','c5',  
'c6','c7', 'c8', 'c9',  'ind_plando', 'long_sup15', 'long_inf15',  
'pente', 'est', 'sud','ouest', 'nord' ,'reg_hydriq', 'prof_sol',  
'pierro', 'efferv', 'struct','drainage','texture', 'route1_pond',  
'route2_pond',
'pourcactif', 'tx_chomage', 'pourcagric', 'pourc_jeunes', 'pop99',  
'rev_imp_foyer','eq_CONC', 'eq_sante', 'eq_edu', 'sold_nat',
'sold_mig', 'tps_dom_emp','TXEMPLOI','ORIECO','dist_paris','axe1',  
'axe2', 'axe3', 'dist_protect','urbanisation','pays_incli','pays_alti'))
# after comes the moment matrix (triangular)

ram_tab<-specify.model()
type_paysage->pays_alti,NA,1
type_paysage->pays_incli, pays2, NA
pedo->reg_hydriq, NA, 1
pedo->prof_sol, ped8, NA
pedo->pierro, ped9, NA
pedo->efferv, ped10, NA
pedo->struct, ped11, NA
pedo->drainage, ped12, NA
pedo->texture, ped13, NA
adj_99->c1, NA,1
adj_99->c2, adj2,NA
adj_99->c3, adj3,NA
adj_99->c4, adj4,NA
adj_99->c5, adj5,NA
adj_99->c6, adj6,NA
adj_99->c7, adj7,NA
adj_99->c8, adj8,NA
adj_99->c9, adj9,NA
etat_hexa->axe1, NA, 1
etat_hexa->axe2, et2, NA
etat_hexa->axe3, et3, NA
socioBV->sold_mig, BV1, NA
socioBV->sold_nat, BV2, NA
socioBV->TXEMPLOI, BV3, NA
socioBV->ORIECO, BV4, NA
socioBV->tps_dom_emp, NA, 1
eqBV->eq_CONC, NA, 1
eqBV->eq_sante, eq2, NA
eqBV->eq_edu, eq3, NA
socio_com->pourcactif , NA, 1
socio_com->tx_chomage, com2, NA
socio_com->pourcagric, com3, NA
socio_com->pourc_jeunes, com4, NA
socio_com->pop99, com5, NA
socio_com->rev_imp_foyer, com7, NA
access_hexa->route1_pond, NA, 1
access_hexa->route2_pond, acc2, NA
hydro->ind_plando, NA, 1
hydro->long_sup15, eau2, NA
hydro->long_inf15, eau3, NA
topog->pente, NA, 1
topog->est, top2, NA
topog->sud, top3, NA
topog->nord, top4, NA
topog->ouest, top5, NA
dist_protect-> urbanisation, cor1,NA
dist_protect-> adj_99, cor2, NA
dist_protect-> etat_hexa, cor3, NA
topog-> urbanisation, cor4, NA
topog-> adj_99, cor5, NA
topog-> etat_hexa, cor6, NA
topog-> access_hexa, cor7, NA
topog<->hydro, cor8, NA
topog<->pedo, cor9, NA
pedo-> urbanisation, cor10, NA
pedo-> adj_99, cor11, NA
pedo-> etat_hexa, cor12, NA
pedo<->hydro, cor1, NA
hydro-> urbanisation, cor13, NA
hydro-> adj_99, cor14, NA
hydro-> etat_hexa, cor15, NA
access_hexa-> urbanisation, cor16, NA
access_hexa-> etat_hexa, cor17, NA
socio_com-> etat_hexa, cor18, NA
socio_com-> adj_99, cor19, NA
socio_com-> urbanisation, cor20, NA
dist_paris-> socio_com, cor21, NA
dist_paris-> access_hexa, cor22, NA
dist_paris-> adj_99, cor23, NA
dist_paris-> etat_hexa, cor24, NA
dist_paris-> urbanisation, cor25, NA
dist_paris-> socioBV, cor26, NA
socioBV-> eqBV, cor27, NA
socioBV-> urbanisation, cor28, NA
socioBV-> adj_99, cor29, NA
socioBV-> etat_hexa, cor30, NA
eqBV-> etat_hexa, cor31, NA
eqBV-> adj_99, cor32, NA
eqBV-> urbanisation, cor33, NA
etat_hexa-> urbanisation, cor34, NA
etat_hexa<-> adj_99, cor35, NA
adj_99-> urbanisation, cor36, NA
type_paysage-> urbanisation, cor37, NA
type_paysage-> adj_99, cor38, NA
type_paysage-> etat_hexa, cor39, NA
dist_paris<->dist_paris, auto1, NA
dist_protect<->dist_protect, auto2, NA
c1 <-> c1, auto4, NA
c2 <-> c2 , auto5, NA
c3 <->  c3 , auto6, NA
c4 <->  c4 , auto7, NA
c5 <->  c5 , auto8, NA
c6 <->  c6 , auto9, NA
c7 <->  c7 , auto10, NA
c8 <-> c8 , auto11, NA
c9 <-> c9 , auto12, NA
ind_plando <->  ind_plando, auto13, NA
long_sup15 <-> long_sup15 , auto14, NA
long_inf15 <->  long_inf15  , auto15, NA
pente <-> pente , auto16, NA
est<->  est , auto17, NA
sud <->  sud , auto18, NA
ouest<-> ouest , auto19, NA
nord <->  nord , auto20, NA
reg_hydriq <-> reg_hydriq , auto21, NA
prof_sol<-> prof_sol , auto22, NA
pierro <-> pierro , auto23, NA
efferv <->  efferv , auto24, NA
struct <-> struct , auto25, NA
drainage <-> drainage, auto26, NA
texture <->  texture , auto27, NA
route1_pond  <->route1_pond  , auto30, NA
route2_pond <-> route2_pond , auto31, NA
pourcactif  <->  pourcactif , auto32, NA
tx_chomage <->  tx_chomage, auto33, NA
pourcagric <-> pourcagric , auto34, NA
pourc_jeunes<-> pourc_jeunes  , auto36, NA
pop99<-> pop99  , auto36, NA
rev_imp_foyer <->   rev_imp_foyer , auto38, NA
eq_CONC <-> eq_CONC, auto39, NA
eq_sante <->eq_sante , auto40, NA
eq_edu<->eq_edu   , auto41, NA
sold_nat<->  sold_nat , auto42, NA
sold_mig  <->  sold_mig  , auto43, NA
tps_dom_emp  <->  tps_dom_emp , auto44, NA
TXEMPLOI  <-> TXEMPLOI  , auto45, NA
ORIECO  <-> ORIECO  , auto46, NA
axe1  <->  axe1 , auto47, NA
axe2  <->  axe2 , auto48, NA
axe3  <-> axe3 , auto49, NA
pays_incli<->pays_incli, auto70, NA
pays_alti<->pays_alti, auto71, NA
urbanisation<->  urbanisation , auto50, NA
type_paysage <-> type_paysage ,  NA,1
adj_99  <-> adj_99 , NA  ,1
socioBV  <-> socioBV ,  NA,1
eqBV  <-> eqBV  , NA ,1
socio_com  <-> socio_com  , NA,1
access_hexa <-> access_hexa , NA,1
hydro  <-> hydro ,  NA ,1
topog <->  topog ,  NA ,1
pedo  <->  pedo  ,  NA ,1
eqBV  <->  eqBV ,  NA ,1
etat_hexa<->etat_hexa,  NA ,1

sem_dyn<-sem(ram_tab, moment_tab, N=1176, raw=T,  
fixed.x=c("pays_alti","reg_hydriq", "c1","axe1", "tps_dom_emp",  
"pourcactif",
"route1_pond","ind_plando","pente"), par.size="ones")


Any help would be greatly appreciate.

Thank you,

Anne