Which value does Modeler use if a string has been input into a numeric field?

When Modeler encounters a string input in a numeric field, it typically assigns a value of $null$. This signifies that the data is not valid or cannot be interpreted as a number. Using $null$ is a standard approach in many data processing systems to represent missing or undefined values, making it clear that the absence of a numeric value is intentional rather than an error or miscalculation.

In contrast, an empty string might suggest that there is a value, albeit one that is blank, while -999 and 0 are often used as placeholders or default values in other contexts but do not imply the same meaning as $null$. These values could potentially confuse data interpretation, as they might be misread as legitimate numeric entries rather than indicators of missing or invalid data. Hence, assigning $null$ helps maintain clarity and control over data integrity when dealing with mixed data types within a dataset.