[amelia] Question about Amelia II for Missing not at random (MNAR)

Dear All, I am Ph.D student at Chulalongkorn University in Thailand, I use your package to impute missing data assump MAR and MNAR. I don't have problem to impute under MAR, but I don't know how to impute MNAR. My MNAR data generate under IRT model(3-PL); n<-500 ## number of examinee I<-20 ## number of items num.imp<-5 ##number of imputations p.missing<-c(0.09, 0.01) #prob of missing theta<-sort(rnorm(n,0,1)) #ability a<-rnorm(I,0.5,0.1) #discrimination b<-rnorm(I,0,1) #difficulty c<-runif(I,0,0.25) #guess Only item 1-4 have missing data. If the response to each items was a 1 (correct), the probability of missing for each items was 1%. If the response was a 0 (incorrect), the probability of missing was 9%. Thus, the probability of missing each items was linked to the response of each items itself (an unknown characteristic in real missing data situations). Could you please tell me function or how to impute data under my situation. I'am looking forward your advice. Sincerely yours, Kamontip Srihaset