df.unobs.y1 <- copy(df.unobs)
         df.unobs.y1[[response.var]] <- 1
         df.unobs.y0 <- copy(df.unobs)
-        df.unobs.y0[[response.var]] <- 1
+        df.unobs.y0[[response.var]] <- 0
         
         ## integrate out y
         outcome.model.matrix.y1 <- model.matrix(outcome_formula, df.unobs.y1)
         if(outcome_family$family == "gaussian"){
             sigma.y <- params[param.idx]
             param.idx <- param.idx + 1
+
+            #  outcome_formula likelihood using linear regression
             ll.y.obs <- dnorm(y.obs, outcome.params %*% t(outcome.model.matrix),sd=sigma.y, log=TRUE)
         }
         
 
         if( (proxy_family$family=="binomial") & (proxy_family$link=='logit')){
             ll.w.obs <- vector(mode='numeric',length=dim(proxy.model.matrix)[1])
+
+            # proxy_formula likelihood using logistic regression
             ll.w.obs[proxy.obs==1] <- plogis(proxy.params %*% t(proxy.model.matrix[proxy.obs==1,]),log=TRUE)
             ll.w.obs[proxy.obs==0] <- plogis(proxy.params %*% t(proxy.model.matrix[proxy.obs==0,]),log=TRUE, lower.tail=FALSE)
         }
 
         if( (truth_family$family=="binomial") & (truth_family$link=='logit')){
             ll.x.obs <- vector(mode='numeric',length=dim(truth.model.matrix)[1])
+
+            # truth_formula likelihood using logistic regression
             ll.x.obs[truth.obs==1] <- plogis(truth.params %*% t(truth.model.matrix[truth.obs==1,]),log=TRUE)
             ll.x.obs[truth.obs==0] <- plogis(truth.params %*% t(truth.model.matrix[truth.obs==0,]),log=TRUE, lower.tail=FALSE)
         }
         
+        # add the three likelihoods
         ll.obs <- sum(ll.y.obs + ll.w.obs + ll.x.obs)
 
         ## likelihood for the predicted data
             outcome.model.matrix.x0 <- model.matrix(outcome_formula, df.unobs.x0)
             outcome.model.matrix.x1 <- model.matrix(outcome_formula, df.unobs.x1)
             if(outcome_family$family=="gaussian"){
+
+                # likelihood of outcome
             ll.y.x0 <- dnorm(outcome.unobs, outcome.params %*% t(outcome.model.matrix.x0), sd=sigma.y, log=TRUE)
             ll.y.x1 <- dnorm(outcome.unobs, outcome.params %*% t(outcome.model.matrix.x1), sd=sigma.y, log=TRUE)
             }
                 ll.w.x0 <- vector(mode='numeric', length=dim(df.unobs)[1])
                 ll.w.x1 <- vector(mode='numeric', length=dim(df.unobs)[1])
 
+                # likelihood of proxy
                 ll.w.x0[proxy.unobs==1] <- plogis(proxy.params %*% t(proxy.model.matrix.x0[proxy.unobs==1,]), log=TRUE)
                 ll.w.x1[proxy.unobs==1] <- plogis(proxy.params %*% t(proxy.model.matrix.x1[proxy.unobs==1,]), log=TRUE)
 
 
             if(truth_family$link=='logit'){
                 truth.model.matrix <- model.matrix(truth_formula, df.unobs.x0)
-                ll.x.x0 <- plogis(truth.params %*% t(truth.model.matrix), log=TRUE)
-                ll.x.x1 <- plogis(truth.params %*% t(truth.model.matrix), log=TRUE, lower.tail=FALSE)
+                # likelihood of truth
+                ll.x.x1 <- plogis(truth.params %*% t(truth.model.matrix), log=TRUE)
+                ll.x.x0 <- plogis(truth.params %*% t(truth.model.matrix), log=TRUE, lower.tail=FALSE)
             }
         }