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set.seed(1)
n = 1000
nclass = 2
nitem = 2
nresp = c(2,2)

#class gamma
gamma = c(.30,.70)

#item - response prob
rho = list(
  matrix(c(.8,.2,
           .1,.9), 2,2,byrow = T),
  
  matrix(c(.9,.1,
           .1,.9), 2,2,byrow = T))

item = matrix(NA, nrow = n, ncol = nitem) # ; item

set.seed(1)
for (c in 1:nclass){
  for (i in 1:n){
    for (m in 1:nitem){
      item[i,m] = sample(x=nresp[m], size = 1, replace = T, prob = rho[[m]][c,])      
    }
  }  
}
#item
library(poLCA)
## 필요한 패키지를 로딩중입니다: scatterplot3d
## 필요한 패키지를 로딩중입니다: MASS
f =  cbind(V1,V2)~1
item.lc2 = as.data.frame(item)
test.lc2 = poLCA(f, item.lc2, nclass=2)
## Conditional item response (column) probabilities,
##  by outcome variable, for each class (row) 
##  
## $V1
##            Pr(1)  Pr(2)
## class 1:  0.2729 0.7271
## class 2:  0.0631 0.9369
## 
## $V2
##            Pr(1)  Pr(2)
## class 1:  0.1074 0.8926
## class 2:  0.1019 0.8981
## 
## Estimated class population shares 
##  0.1997 0.8003 
##  
## Predicted class memberships (by modal posterior prob.) 
##  0.105 0.895 
##  
## ========================================================= 
## Fit for 2 latent classes: 
## ========================================================= 
## number of observations: 1000 
## number of estimated parameters: 5 
## residual degrees of freedom: -2 
## maximum log-likelihood: -667.5553 
##  
## AIC(2): 1345.111
## BIC(2): 1369.649
## G^2(2): 9.787147e-10 (Likelihood ratio/deviance statistic) 
## X^2(2): 9.901484e-10 (Chi-square goodness of fit) 
##  
## ALERT: negative degrees of freedom; respecify model 
## 

###########poLCA 논문 자료 연습####################### ###################################################### # Basic latent class modeling with the carcinoma data ######################################################

## 'data.frame':    1202 obs. of  4 variables:
##  $ PURPOSE : Factor w/ 3 levels "Good","Depends",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ ACCURACY: Factor w/ 2 levels "Mostly true",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ UNDERSTA: Factor w/ 2 levels "Good","Fair/Poor": 1 1 1 1 1 1 1 1 1 1 ...
##  $ COOPERAT: Factor w/ 3 levels "Interested","Cooperative",..: 1 1 1 1 1 1 1 1 1 1 ...
## Conditional item response (column) probabilities,
##  by outcome variable, for each class (row) 
##  
## $PURPOSE
##             Good Depends Waste of time
## class 1:  0.2154  0.2066        0.5780
## class 2:  0.8953  0.0579        0.0468
## 
## $ACCURACY
##           Mostly true Not true
## class 1:       0.0297   0.9703
## class 2:       0.6367   0.3633
## 
## $UNDERSTA
##             Good Fair/Poor
## class 1:  0.7422    0.2578
## class 2:  0.8327    0.1673
## 
## $COOPERAT
##           Interested Cooperative Impatient
## class 1:      0.6478      0.2498    0.1024
## class 2:      0.8840      0.1043    0.0117
## 
## Estimated class population shares 
##  0.1923 0.8077 
##  
## Predicted class memberships (by modal posterior prob.) 
##  0.1864 0.8136 
##  
## ========================================================= 
## Fit for 2 latent classes: 
## ========================================================= 
## number of observations: 1202 
## number of estimated parameters: 13 
## residual degrees of freedom: 22 
## maximum log-likelihood: -2783.268 
##  
## AIC(2): 5592.536
## BIC(2): 5658.729
## G^2(2): 79.33723 (Likelihood ratio/deviance statistic) 
## X^2(2): 93.25329 (Chi-square goodness of fit) 
## 
##  Interested Cooperative Impatient
##    4.940145   0.7603678 0.1613179

5. Two Examples

## Conditional item response (column) probabilities,
##  by outcome variable, for each class (row) 
##  
## $A
##            Pr(1)  Pr(2)
## class 1:  0.0000 1.0000
## class 2:  0.8835 0.1165
## 
## $B
##            Pr(1)  Pr(2)
## class 1:  0.0169 0.9831
## class 2:  0.6456 0.3544
## 
## $C
##            Pr(1)  Pr(2)
## class 1:  0.2391 0.7609
## class 2:  1.0000 0.0000
## 
## $D
##            Pr(1)  Pr(2)
## class 1:  0.4589 0.5411
## class 2:  1.0000 0.0000
## 
## $E
##            Pr(1)  Pr(2)
## class 1:  0.0214 0.9786
## class 2:  0.7771 0.2229
## 
## $F
##            Pr(1)  Pr(2)
## class 1:  0.5773 0.4227
## class 2:  1.0000 0.0000
## 
## $G
##            Pr(1)  Pr(2)
## class 1:  0.0000 1.0000
## class 2:  0.8835 0.1165
## 
## Estimated class population shares 
##  0.5012 0.4988 
##  
## Predicted class memberships (by modal posterior prob.) 
##  0.5 0.5 
##  
## ========================================================= 
## Fit for 2 latent classes: 
## ========================================================= 
## number of observations: 118 
## number of estimated parameters: 15 
## residual degrees of freedom: 103 
## maximum log-likelihood: -317.2568 
##  
## AIC(2): 664.5137
## BIC(2): 706.0739
## G^2(2): 62.36543 (Likelihood ratio/deviance statistic) 
## X^2(2): 92.64814 (Chi-square goodness of fit) 
## 

## Conditional item response (column) probabilities,
##  by outcome variable, for each class (row) 
##  
## $A
##            Pr(1)  Pr(2)
## class 1:  0.4872 0.5128
## class 2:  0.0000 1.0000
## class 3:  0.9427 0.0573
## 
## $B
##            Pr(1)  Pr(2)
## class 1:  0.0000 1.0000
## class 2:  0.0191 0.9809
## class 3:  0.8621 0.1379
## 
## $C
##            Pr(1)  Pr(2)
## class 1:  1.0000 0.0000
## class 2:  0.1425 0.8575
## class 3:  1.0000 0.0000
## 
## $D
##            Pr(1)  Pr(2)
## class 1:  0.9424 0.0576
## class 2:  0.4138 0.5862
## class 3:  1.0000 0.0000
## 
## $E
##            Pr(1)  Pr(2)
## class 1:  0.2494 0.7506
## class 2:  0.0000 1.0000
## class 3:  0.9449 0.0551
## 
## $F
##            Pr(1)  Pr(2)
## class 1:  1.0000 0.0000
## class 2:  0.5236 0.4764
## class 3:  1.0000 0.0000
## 
## $G
##            Pr(1)  Pr(2)
## class 1:  0.3693 0.6307
## class 2:  0.0000 1.0000
## class 3:  1.0000 0.0000
## 
## Estimated class population shares 
##  0.1817 0.4447 0.3736 
##  
## Predicted class memberships (by modal posterior prob.) 
##  0.1949 0.4322 0.3729 
##  
## ========================================================= 
## Fit for 3 latent classes: 
## ========================================================= 
## number of observations: 118 
## number of estimated parameters: 23 
## residual degrees of freedom: 95 
## maximum log-likelihood: -293.705 
##  
## AIC(3): 633.41
## BIC(3): 697.1357
## G^2(3): 15.26171 (Likelihood ratio/deviance statistic) 
## X^2(3): 20.50335 (Chi-square goodness of fit) 
## 
## Conditional item response (column) probabilities,
##  by outcome variable, for each class (row) 
##  
## $A
##            Pr(1)  Pr(2)
## class 1:  0.0000 1.0000
## class 2:  0.6112 0.3888
## class 3:  0.9411 0.0589
## class 4:  0.0000 1.0000
## 
## $B
##            Pr(1)  Pr(2)
## class 1:  0.0404 0.9596
## class 2:  0.0000 1.0000
## class 3:  0.8713 0.1287
## class 4:  0.0000 1.0000
## 
## $C
##            Pr(1)  Pr(2)
## class 1:  0.2688 0.7312
## class 2:  1.0000 0.0000
## class 3:  1.0000 0.0000
## class 4:  0.1516 0.8484
## 
## $D
##            Pr(1)  Pr(2)
## class 1:  0.6788 0.3212
## class 2:  1.0000 0.0000
## class 3:  1.0000 0.0000
## class 4:  0.2415 0.7585
## 
## $E
##            Pr(1)  Pr(2)
## class 1:  0.0478 0.9522
## class 2:  0.2503 0.7497
## class 3:  0.9477 0.0523
## class 4:  0.0000 1.0000
## 
## $F
##            Pr(1)  Pr(2)
## class 1:  1.0000 0.0000
## class 2:  1.0000 0.0000
## class 3:  1.0000 0.0000
## class 4:  0.2115 0.7885
## 
## $G
##            Pr(1)  Pr(2)
## class 1:  0.0000 1.0000
## class 2:  0.4679 0.5321
## class 3:  1.0000 0.0000
## class 4:  0.0000 1.0000
## 
## Estimated class population shares 
##  0.2098 0.1519 0.3696 0.2687 
##  
## Predicted class memberships (by modal posterior prob.) 
##  0.2881 0.1271 0.3729 0.2119 
##  
## ========================================================= 
## Fit for 4 latent classes: 
## ========================================================= 
## number of observations: 118 
## number of estimated parameters: 31 
## residual degrees of freedom: 87 
## maximum log-likelihood: -289.7889 
##  
## AIC(4): 641.5778
## BIC(4): 727.469
## G^2(4): 7.429509 (Likelihood ratio/deviance statistic) 
## X^2(4): 11.64706 (Chi-square goodness of fit) 
## 

election data : 2000명의 미국인을 대상으로 선거 조사한거임


단락 분리해보자

4개의 초이스


(1) extremely well
(2) quite well
(3) not too well
(4) not well at all