Performs comprehensive validation of input parameters for the frontier function,
checking data types, required columns, and parameter bounds.
Usage
validate_inputs(x, threshold, start_index)
Arguments
- x
A data.frame that should contain 'cost' and 'impact' columns
- threshold
Numeric value representing willingness-to-pay threshold
- start_index
Integer representing the starting row index
Value
NULL (function stops execution with error if validation fails)