EARLIER Returns the current value of the specified column in an outer evaluation pass of the mentioned column.
EARLIER is useful for nested calculations where you want to use a certain value as an input and produce calculations based on that input. In Microsoft Excel, you can do such calculations only within the context of the current row; however, in DAX you can store the value of the input and then make calculation using data from the entire table.
EARLIER is mostly used in the context of calculated columns.
Column – A column or expression that resolves to a column.
Num – (Optional) A positive number to the outer evaluation pass.
The next evaluation level out is represented by 1; two levels out is represented by 2 and so on.
When omitted default value is 1.
The current value of row, from column, at number of outer evaluation passes.