These kinds of checks are the ones you could also name common sense checks, since they mainly relate to checks involving normal expectations of your data. Consider for instance a table where a column is expected to show a summary, for example, the mean of some other columns, like for instance the mean of the monthly sales reported within previous columns. A consistency check here would be checking, even for just some records, if this column actually shows that average. Getting back to our customer_list table, if we know that the total number of customers of our company is nearly 100, finding 10 customers would surely imply a data quality problem. Even if these kinds of checks can appear to be quite basic and not very sophisticated, you should never forget to perform them, since they are quite effective in letting you catch even big issues on your data.