See Data Quality Charts
Once the data is shown for data preview, Ideata will show a status bar above each column to provide you an overview of the data quality. Following is how you can interpret the statistical bar:
Green - number of values Parsed Successfully
Red- number of values don't parsed
Yellow - number of missing values
You can select the one which are null or invalid and it will highlight those column values and its corresponding values. System will also suggest you operations which you can possibly perform to improve data quality in left suggestion panel.