Re: [R] R Package: mmlcr and/or flexmix

From: <Friedrich.Leisch_at_tuwien.ac.at>
Date: Tue 12 Apr 2005 - 17:25:04 EST

>>>>> On Tue, 12 Apr 2005 00:44:17 -0400, >>>>> Geller, Scott (IHG) (GS() wrote:

> Greetings
> I'm a relatively new R user and I'm trying to build a latent class model.
> I've used the 'R Site Search' and it appears there's not much dialogue on
> these packages

[...]

> libray(flexmix)

> m1<-flexmix(nts ~ first_brand_HOLIDAY+ perc_zone1+ perc_Group_nights+
> perc_num_asian+ DaysBetweenStays+ CROStays+ DaysSinceLastStay+
> wghtmean_median_age_pop100+ perc_num_white+ perc_num_hispanic+
> perc_CROStays+ numMonthsActive+ WEBStays+ property_loyalty+ perc_NoZone+
> rho+ PCR_Dummy_class+ ltgold1+ ltgold3+ p_hat_PCR, data = data, k = 2, model
> = FLXglm(family = "poisson"))

> rm1<-refit(m1)

> summary(rm1)
 

[ Scott sent me in private a subset of the data ]

For me this seems to work fine:

R> set.seed(123)
R> m1<-flexmix(nts ~ first_brand_HOLIDAY+ perc_zone1+ perc_Group_nights+

+ perc_num_asian+  DaysBetweenStays+ CROStays+ DaysSinceLastStay+
+ wghtmean_median_age_pop100+ perc_num_white+ perc_num_hispanic+
+ perc_CROStays+ numMonthsActive+ WEBStays+ property_loyalty+ perc_NoZone+
+ rho+ PCR_Dummy_class+ ltgold1+ ltgold3+ p_hat_PCR, data = data, k = 2, model
+ = FLXglm(family = "poisson"))

R> m1

Call:
flexmix(formula = nts ~ first_brand_HOLIDAY + perc_zone1 + perc_Group_nights +

    perc_num_asian + DaysBetweenStays + CROStays + DaysSinceLastStay +     wghtmean_median_age_pop100 + perc_num_white + perc_num_hispanic +     perc_CROStays + numMonthsActive + WEBStays + property_loyalty +     perc_NoZone + rho + PCR_Dummy_class + ltgold1 + ltgold3 +     p_hat_PCR, data = data, k = 2, model = FLXglm(family = "poisson"))

Cluster sizes:
  1 2
 93 906

convergence after 49 iterations

R> rm1<-refit(m1)
R>
R> summary(rm1)

Call:
refit(m1)

Component 1 :

                              Estimate  Std. Error z value  Pr(>|z|)
(Intercept)                 1.0108e+00  6.4399e-01  1.5696 0.1164971
first_brand_HOLIDAY        -9.3504e-01  4.6151e-01 -2.0261 0.0427594
perc_zone1                  1.3936e-01  7.4383e-01  0.1874 0.8513845
...

Component 2 :
                              Estimate  Std. Error z value  Pr(>|z|)
(Intercept)                 1.00799714  0.39133294  2.5758   0.01000
first_brand_HOLIDAY        -0.07928984  0.15935997 -0.4976   0.61880
perc_zone1                  0.01208886  0.42596711  0.0284   0.97736
...

So I cannot reproduce the problem. Is maybo one cluster in your solution empty? The EM algorithm can end up in a local optimum with one cluster empty ... either run flexmix() several times by hand or use stepFlexmix() to do so automatically.

HTH,

-- 
-------------------------------------------------------------------
                        Friedrich Leisch 
Institut für Statistik                     Tel: (+43 1) 58801 10715
Technische Universität Wien                Fax: (+43 1) 58801 10798
Wiedner Hauptstraße 8-10/1071
A-1040 Wien, Austria             http://www.ci.tuwien.ac.at/~leisch

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Received on Tue Apr 12 17:30:39 2005

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