sothere are lots of things to watch out forand the previous list names just the main ones to be aware of remembergarbage ingarbage out your model is only as good as the data that you give to itand this is extremelyextremely trueyou can have very simple model that performs very well if you give it large amount of clean dataand it could actually outperform complex model on more dirty dataset thereforemaking sure that you have enough dataand high-quality data is often most of the battle you' be surprised how simple some of the most successful algorithms used in the real world are they're only successful by virtue of the quality of the data going into itand the amount of data going into it you don' always need fancy techniques to get good results oftenthe quality and quantity of your data counts just as much as anything else always question your resultsyou don' want to go back and look for anomalies in your input data only when you get result that you don' like that will introduce an unintentional bias into your results where you're letting results that you likeor expectgo through unquestionedrightyou want to question things all the time to make sure that you're always looking out for these things because even if you find result you likeif it turns out to be wrongit' still wrongit' still going to be informing your company in the wrong direction that could come back to bite you later on as an examplei have website called no-hate news it' non-profitso ' not trying to make any money by telling you about it let' say just want to find the most popular pages on this website that own that sounds like pretty simple problemdoesn' iti should just be able to go through my web logsand count up how many hits each page hasand sort themrighthow hard can it be?wellturns out it' really hardsolet' dive into this example and see why it' difficultand see some examples of real-world data cleanup that has to happen cleaning web log data we're going to show the importance of cleaning your data have some web log data from little website that own we are just going to try to find the top viewed pages on that website sounds pretty simplebut as you'll seeit' actually quite challengingsoif you want to follow alongthe pq bhftjqzoc is the notebook that we're working from here let' start