As analysisng errors aroud us, we could find them in the stages of gathering, interpreting information and anticipation stage. There were some cases that accidents happened from errors. It is hard and define to find errors in stages we are working. Individually, when making them unconsciously to the final stage, it would result in horrible outcomes. For example, when working on PMA of our modules, if one is working on them, after reading the question wrongly and find errors when making conclusion just before deadline, it is so tough decide to redo or submit. In this case "information not observed" could be applied in this case. This is one of the most usual example around us. Furthermore, the kinds of error are inter-related each other, so in this analysis I think the best way is to apdapt as many as we can in errors to prevent them.