2. A system comprising: at least one processor configured to perform: accessing input data comprising: training data comprising a first plurality of data records, each of the first plurality of data records having a numeric data value for each of a plurality of variables; and a second plurality of data records, each of the second plurality of data records having a numeric data value for at least one of the plurality of variables; identifying at least a first not fully specified data record within the second plurality of data records that does not include at least a first numeric data value for at least a first variable of the plurality of variables; determining, automatically and based on the training data, a relationship between the first variable and at least one other variable in the plurality of variables, wherein determining the relationship comprises: generating, using a machine learning technique and the first plurality of records in the training data, a mathematical model representing the relationship between the first variable and the at least one other variable; and obtaining, using the mathematical model representing the relationship between the first variable and the at least one other variable, at least the first numeric data value for the first variable in the first not fully specified data record.
2. A system comprising: at least one processor configured to perform: accessing input data comprising: training data comprising a first plurality of data records, each of the first plurality of data records having a numeric data value for each of a plurality of variables; and a second plurality of data records, each of the second plurality of data records having a numeric data value for at least one of the plurality of variables; identifying at least a first not fully specified data record within the second plurality of data records that does not include at least a first numeric data value for at least a first variable of the plurality of variables; determining, automatically and based on the training data, a relationship between the first variable and at least one other variable in the plurality of variables, wherein determining the relationship comprises: generating, using a machine learning technique and the first plurality of records in the training data, a mathematical model representing the relationship between the first variable and the at least one other variable; and obtaining, using the mathematical model representing the relationship between the first variable and the at least one other variable, at least the first numeric data value for the first variable in the first not fully specified data record. 14. The system according to claim 2 , wherein accessing the input data includes receiving, within a spreadsheet user interface, a selection of the first plurality of data records and the second plurality of data records.