+
+        temp.df <- copy(df)
+        temp.df <- temp.df[,x:=x.obs]
+        mod.caroll.lik <- measerr_mle(temp.df, outcome_formula=outcome_formula, proxy_formula=proxy_formula, truth_formula=truth_formula)
+
+    ## tryCatch({
+    ## mod.calibrated.mle <- mecor(y ~ MeasError(w_pred, reference = x.obs) + z, df, B=400, method='efficient')
+    ## (mod.calibrated.mle)
+    ## (mecor.ci <- summary(mod.calibrated.mle)$c$ci['x.obs',])
+    ## result <- append(result, list(
+    ##                              Bxy.est.mecor = mecor.ci['Estimate'],
+    ##                              Bxy.ci.upper.mecor = mecor.ci['UCI'],
+    ##                              Bxy.ci.lower.mecor = mecor.ci['LCI'])
+    ##                  )
+
+
+
+    fischer.info <- NA
+    ci.upper <- NA
+    ci.lower <- NA
+
+    tryCatch({fischer.info <- solve(mod.caroll.lik$hessian)
+        ci.upper <- coef + sqrt(diag(fischer.info)) * 1.96
+        ci.lower <- coef - sqrt(diag(fischer.info)) * 1.96
+    },
+
+    error=function(e) {result[['error']] <- as.character(e)
+    })
+
+    coef <- mod.caroll.lik$par
+        
+        result <- append(result,
+                         list(Bxy.est.mle = coef['x'],
+                              Bxy.ci.upper.mle = ci.upper['x'],
+                              Bxy.ci.lower.mle = ci.lower['x'],
+                              Bzy.est.mle = coef['z'],
+                              Bzy.ci.upper.mle = ci.upper['z'],
+                              Bzy.ci.lower.mle = ci.lower['z']))
+
+        mod.zhang.lik <- zhang.mle.iv(df)
+        coef <- coef(mod.zhang.lik)
+        ci <- confint(mod.zhang.lik,method='quad')
+        result <- append(result,
+                         list(Bxy.est.zhang = coef['Bxy'],
+                              Bxy.ci.upper.zhang = ci['Bxy','97.5 %'],
+                              Bxy.ci.lower.zhang = ci['Bxy','2.5 %'],
+                              Bzy.est.zhang = coef['Bzy'],
+                              Bzy.ci.upper.zhang = ci['Bzy','97.5 %'],
+                              Bzy.ci.lower.zhang = ci['Bzy','2.5 %']))
+