Traditionally, prize-size curves has been the general name given to lists of timber prices for a range of tree sizes, but strictly a curve is a line on a graph drawn from figures in a schedule. Schedule is the proper technical term, but the traditional name (and its abbreviation PSC) is more familiar.
FIAP contains four standard long-term PSCs prepared by FC, which are suitable for long-term planning decisions. You can view these price-size schedules by selecting GoTo then Price-Size Curves in the Edit or View menus. What is shown are the actual prices used in the current analysis, i.e., updated for inflation to the price base year selected.
1. StdCFGB - Standard conifer prices for Great Britain.
2. StdBLGB - Standard broadleaf prices for Great Britain.
3. StdCFEW - Standard conifer prices for England and Wales.
4. StdCFSC - Standard conifer prices for Scotland.
Besides these standard prices, there is space for four more price-size schedules which you may construct yourself to reflect local conditions. The area where you may do this is to the right of the PSCs. You are taken there by the Create New command in the Custom PSC option in the Prices menu.
The Create New command in the Custom PSC option in the Prices menu enables you to construct a price-size schedule (or curve) from local price data. Instructions are provided on screen, which you can see when you invoke this command, but in outline you give the new PSC a name and then enter as much price information as you have on prices in £/cubic metre for different sizes of tree. From the Prices menu you then select Fill, and all the gaps are filled in using straight-line interpolation.
You can create a schedule with as much or as little information as you have available or consider appropriate. The Fill command fills in what gaps there are, treating the last entered value as a constant, from that size to the highest average tree size in the schedule. You can alter the schedule as much as you like, altering some of your information, deleting unknown prices, and repeating the Fill command. FIAP prompts you to Save the PSC after each use of the fill command - if you are not finished click on no.
In preparing a price-size schedule from your own data, it may be very helpful to be able to look at the curve on a graph, for instance to ensure that there are no unintended blips due to wrongly entered data. Having used the Fill command, use the Graph new PSC command. You are prompted for the
maximum log size you wish to include in the graph; the maximum is 9.00 cubic metres, but the default is 1.00. In the standard conifer price-size schedules, prices do not increase beyond 1.00 m3 and graphing larger log sizes merely reduces the overall detail.
You can keep the graph on the screen while you continue to amend and refine the new PSC. The graph will show any changes you make, automatically if recalculation is set to Auto, or when you press F9. When you no longer want it, get rid of the graph by clicking on it and pressing the delete key on your keyboard.
Having prepared the schedule to your satisfaction, you can use commands in the Prices menu to Print it off for your records, Import it to the part of FIAP where it can be used in current analyses, and/or Save it to disk for future use (see Section 8.6 below).
You may wish to recall from disk a previously prepared price-size schedule and amend it. To do this, select the Amend command from the Prices menu. A dialogue box allows you to select the price-size schedule you want to amend: you may not alter the standard long-term schedules. Having retrieved it from disk, you can delete prices over the range of sizes for which you have improved data, and use the Fill command as described above. Instructions are also provided on screen.
Having prepared or amended a PSC, you can copy it to one of the vacant positions (5. .8) for use in a current analysis. However you must first save the PSC to disk using the Save option in the Custom PSC component of the Prices menu. You will be asked for a filename. All customised PSC’s are kept in the PCFIAP\PSC directory and have the suffix .psc.
With the Import command in the Prices menu a previously prepared price-size schedule (or curve) can be imported from disk and placed in the available price-size schedule positions (5..8) for use in current analysis. The first vacant location is used. If you try and import a PSC when there are already four present a warning message will ask you to remove an existing one. You cannot import one of the standard PSCs.
The Remove command in the Price menu deletes one of the non-standard price-size schedules (or curves) from locations 5..8. You are prompted for the number of the location you wish to remove. On removing a PSC the remaining PSC’s are shifted to the left, leaving the space at the right so care must be taken when undertaking multiple removes. You cannot remove one of the standard PSCs.
It may be helpful to compare on a graph all PSCs currently available for use in analyses. Use the Graph all PSCs command in the Prices menu. You are prompted for the largest log size you wish to include in the graph; the maximum is 9.00 cubic metres, but the default is 1.00. In the standard conifer price-size schedules, prices do not increase beyond 1.00 m3 and graphing larger log sizes merely reduces the overall detail. When you no longer want it, get rid of the graph by clicking on it and pressing the Delete key.
Having prepared a new price-size schedule (or curve), or amended an old one, you may wish to print it for your records. This is done through the Custom PSC command in the Prices menu. Use the Amend Existing command to load up the PSC (select the filename in the dialogue box) if you have moved from this section, then choose Print from the Custom PSC options. You may also want to print a copy of all the price-size schedules currently in use - the four standard schedules and any others you have included, showing the prices current at the time of the analysis, i.e., updated for inflation. (See above).
The Print PSCs command in the Prices menu prints the 4 standard PSCs and all the user created PSCs currently in the PSC sheet. It is also possible to print the user created PSC’s by using the Print PSC, New/Amended PSC option in the File menu.
