What fraction of a capital investment is sunk costs?

To what extent are capital investments sunk costs? This question is address ed by examining the salvage values of discarded metalworking machinery. Eve n though such assets are expected to be non-specific, many discarded assets are scrapped rather than sold on second-hand markets. Econometric results suggest that firms can only expect to get back 20-50 percent of the initial price of a 'new' machine once it is installed. The results also indicate d ifferences in value-age profiles across firms, but provide only weak suppor t for the hypothesis that salvage values are particularly low during recess ions.