So you are collecting data to feed into your measurements systems to get results. If you enter crappy data, your measurements will be crappy and you will get crappy results
When you are collecting data/info; beware of any human error, data entry error, outdated data, process errors, biases, spams and malicious data. Also keep your measurements equations and processes updated all the time with all important factors included
The quality of your measurements depends on the quality of the data fed into the measurements processes and how good are your measurements' processes
- Sometimes you will find that you or the people working with you knowing that there is something wrong with the data they are entering of with the measurements but they are ignoring them because correcting the error will make them look worse; for example lowering the number of website visits, cut the sales numbers in half …etc.). A very basic human nature is that we want to look good, and looking worse puts us out of our comfortable zone.
However, know that "Honest Systems" don't give a damn about your feelings! All they care about is getting true numbers and giving you true, objective results.