DPL Decision Tree Software Support - Frequently Asked Questions & Tips

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FREQUENTLY ASKED QUESTIONS

Where is my Advanced Topics Guide?
The Advanced Topics Guide is soft copy only. If you selected to have it installed when you installed DPL, it is in a directory called Documentation underneath where you installed DPL. If you did not select to have it installed, re-install DPL and select it as an option on the Components page of the installation script.

What order should my data be in in Excel for Initialization Links?
If the node whose data resides in Excel is not conditioned, then the order of the data should match the order of the states of the node (e.g., Low, Nominal, High). The named range containing the data can be either in a row or a column in Excel. If the node is conditioned, then the reading order (i.e., across a row then down to the next row) of the data should match the order in which it appears in the node definition dialog window. For example, let Node B have three states called Low, Nominal and High. Let Node A have two states called Yes and No. Let Node B be conditioned by Node A. The order of the data for Node B in Excel should be Low|Yes, Nominal|Yes, High|Yes, Low|No, Nominal|No, High|No. Either layout below is acceptable:

	Low	Nominal	High
Yes	.	.	.
No	.	.	.

Yes			No
Low	Nominal	High	Low	Nominal	High
.	.	.	.	.	.

The following layout is unacceptable for the example above:

	Yes	No
Low	.	.
Nominal	.	.
High	.	.

I get an error when activating online. What should I do?
The connection to our Activation Server may be being blocked by your firewall. Send an email to support@syncopation.com with your serial number, installation key and machine information. Your machine information can be found in the four boxes below where you enter the installation key in the Activation dialog. We will send you an activation key by email.
Is DPL Release 6.0 compatible with Excel?
Yes, DPL Release 6.0 is compatible with Excel versions 8.0 (Office 97) and later. Our surveys indicate that over 90% of DPL Professional users link DPL to Excel.
Is DPL Release 6.0 compatible with Lotus 1-2-3?
No DPL Release 6.0 is not compatible with Lotus 1-2-3. Contact support if you use Lotus 1-2-3.
How many endpoints (sometimes called leaf nodes) can DPL Release 6.0 handle?
There is no fixed limit. At some point, either your computer's memory is exhaused or (more often) decision analysis runs take longer than you would like to wait. Every model is different, but most users find that with a cashflow spreadsheet of moderate size they are able to work with thousands of endpoints. For a model without a spreadsheet, or with a spreadsheet which has been converted to DPL code, millions of endpoints (or more) can be tractable.
Should I start building my DPL model with an Influence Diagram or a Decision Tree?
This is a matter of taste. Most decision analysis practitioners recommend starting with an influence diagram, but for models with a conditional structure (i.e., "If we decide not to do the marketing test then ...") starting with a tree is often more intuitive.
Why can't I run a Monte Carlo simulation on my (discrete) model?
If your model is a discrete tree (i.e., it doesn't contain any continuous chance nodes), a Decision Analysis run with the Discrete Tree Simulation evaluation method produces exactly the same results as Monte Carlo, and runs faster.
Should I build my spreadsheet model before or after my DPL model?
Many analyses begin with a cash flow model which must be used in order for the analysis to be credible. You can easily have DPL build a DPL model from such a cash flow speadsheet. Starting with this basic model you can conduct sensitivity analyses to determine which variables have the biggest impact. You will typically want to treat these variables as uncertain by changing them into chance nodes. Subsequently you can add decisions to your model. Adding decisions will usually require some changes to the spreadsheet to incorporate the switches associated with each decision.
I thought DPL was from Applied Decision Analysis/Standard & Poors/PricewaterhouseCoopers?
DPL has a rich history. Syncopation Software has been developing, marketing and supporting DPL since signing an agreement with PricewaterhouseCoopers on 1 July 2003. We are first and foremost a software company, and are committed to satisfying our users and advancing DPL in the marketplace. The founders of Syncopation have been involved with DPL since its inception in 1991.
Why are DPL's default probabilities 30%/40%/30%?
Those probabilites are the best three-state approximation to a normal distribution when used with values from the 10th, 50th and 90th percentiles of the normal cumulative distribution function. Therefore, if you have estimated the 10th/50th/90th percentiles for sensitivity analysis, and you believe your uncertainties are normally distributed, you can progress from sensitivity analysis to decision/risk analysis quickly.
Why isn't my decision tree updated when I add nodes to the influence diagram?
DPL will build a default decision tree while you're working in the influence diagram. However, once you change the decision tree, DPL assumes you've taken over tree modelling, and doesn't make further updates. If you'd like to get back to having DPL update the tree, choose Model | Build Default Tree. DPL will overwrite your tree with a new default tree.
DPL runs my model even though there are detached nodes in the influence diagram.
Because DPL models are a combination of an influence diagram and a decision tree, DPL will run models which appear incomplete to users accustomed to working with an influence diagram alone. In particular, arcs which indicate timing can be omitted when the sequence of nodes is indicated in the decision tree.
How can I make my analysis run faster?
Runtimes are affected by many factors, including the size and structure of your decision tree, the size of your spreadsheet (if applicable) and the DPL optimization settings in effect. Click here for tips on reducing runtimes.
I tried converting my spreadsheet, but now I get an "@na encountered" error.
DPL supports the Excel functions that are most commonly found in cash flow spreadsheets. If you see an "@na" error after converting, your spreadsheet may contain functions not supported by DPL. See the note on Excel functions in DPL for more information.