The practice of checking, correcting, labeling, and normalizing data. Common activities related to data hygiene include checking for accuracy, ensuring formats are the same in each dataset (such as the format for date & time), determining or creating a unique identifier (such as an email address or phone number, which allows combining one dataset with others), and categorizing data.
"We have a lot of responses from past marketing efforts, but the data hygiene is very poor—none of the questions asked of users were the same, and the contact information is not checked for accuracy or typos. It would be cheaper to start over than fix it."
