9.1.6 Quantitative Assessment of Project Dimensions  Whether preservation is carried out autonomously in-house, or partly or fully outsourced, an indispensable pre-condition for seriously planning preservation is the quantitative assessment of the project. Serious and costly mistakes are often made by underestimating the amount of work needed for the optimal signal extraction from original carriers. Therefore, the first step is to count the numbers of carriers and their playing time.With mechanical carriers, compact cassettes, and optical carriers there is a fairly clear relation between the number of carriers and their respective playing times. This may be more complex in the case of magnetic open reel collections as the playing time is dependant on the length of the tape, the speed of recording and the numbers of tracks. However, with good knowledge of the specific collection, some well founded assumptions can often be made which lead to reasonably accurate estimates. In poorly documented or undocumented collections, a situation often encountered in the estates of prominent persons, this assessment can be extremely time consuming.  Once the duration of the carriers to be transferred is assessed, a second important factor is their physical condition. The time factors given in the respective parts of Chapter 5, Signal Extraction from Original Carriers, relate to well preserved items. Any cleaning and restoration measures required may add substantially to transfer times, and must be included in the calculations accordingly.