Dear all,
I am a new Genie user and I have a doubt with Genie.
I tried to find the relationship(network) of some items by using Genie. I followed next steps:
1. I got my file in format csv.
2. Discretization of each row. There are 8 parameters (colums) and 590 rows.
3. Learn new network. I choose Bayesian Research, without change any initial parameters: discrete thresold: 20, iteration: 20, sample size: 50.
4. And I got a network. (Attachment 2)
The problem is, when I repeat step 1-3, without any change (same file, same disrectization, same parameters). However, I got another network in step 4. (Please see attachment 3)
I have no idea why the network changes.
Any answer will be appreciated!!! Many thanks!!!
Bayesian Research -- Different networks with same initial parameter
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Re: Bayesian Research -- Different networks with same initial parameter
You're using random seed value of zero, which means that actual seed is taken from the system clock and a couple of other system values. To obtain repeatable results, use nonzero seed.
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Re: Bayesian Research -- Different networks with same initial parameter
Thanks a lot!!! I put seed 1 and now I get the same network !shooltz[BayesFusion] wrote:You're using random seed value of zero, which means that actual seed is taken from the system clock and a couple of other system values. To obtain repeatable results, use nonzero seed.
Hope you do not mind.... I have another question: as my object is to find the influence value of each parameter related with KEA(my last parameter). I re-constructed the network. I followed these steps:
1. Connect the arcs and build a new network as you can see in this picture. 2. Learn Parameter : match the prameters and update the network. 3. An automatic window is skipped: learn parameters with EM. I choose 'Keep Original' and Confidence '50' (the same number as sample size). 4. Finally I update the network and click on 'Strength of Influence' to get the influence value of each parameter related to KEA.
However, when I repeat again step 1-3 without change any input and click again on 'Strength of influence', the influence value of the parameters changes.
Do you know where the error is? (As Step 1 and 2 are only to match the parameters, I do not think there exist any incoherence, the problem may occur in Step 3).
Thanks in advance!!!
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Re: Bayesian Research -- Different networks with same initial parameter
Apply sensitivity analysis for this. See Using GeNIe | Bayesian Networks | Sensitivity analysis in Bayesian networks chapter in GeNIe manual.find the influence value of each parameter related with KEA(my last parameter)
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Re: Bayesian Research -- Different networks with same initial parameter
shooltz[BayesFusion] wrote:Apply sensitivity analysis for this. See Using GeNIe | Bayesian Networks | Sensitivity analysis in Bayesian networks chapter in GeNIe manual.find the influence value of each parameter related with KEA(my last parameter)
Thanks very much for your prompt reply.
I also tried Sensitivity Analysis, but it changes every time when I rebuild the same network.
I attach two trials for your reference [Sensitivity Analysis & Strength of Influence]. All the previous steps are the same. but the final influence diagram result is different.
Trial 1: follow step 1 -3 I mencioned previously. Trial 2: repite Trial 1 without any changes.
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Re: Bayesian Research -- Different networks with same initial parameter
Don't mix strenght of influence and sensitivity analysis. Use one or the other. I recommend sensitivity analysis for your case.
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Re: Bayesian Research -- Different networks with same initial parameter
I tried Strength of influence firstly, the final influence diagram is different. Then I tried only Sensitivity Analysis, the result is not the same neither.shooltz[BayesFusion] wrote:Don't mix strenght of influence and sensitivity analysis. Use one or the other. I recommend sensitivity analysis for your case.
As the influence diagram varies every time I rebuilt the network (with same steps), I cannot sure the weight that each parameter contributes to the Target (In this case, KEA).
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Re: Bayesian Research -- Different networks with same initial parameter
Post two networks learned with identical seed here, so we can investigate the problem.
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Re: Bayesian Research -- Different networks with same initial parameter
Dear shooltz,shooltz[BayesFusion] wrote:Post two networks learned with identical seed here, so we can investigate the problem.
I tried several times and I find the error! In step 3 I put sample size (confidence level) 50 instead of 100, it causes different results because Genie pick up randomly half of the samples (50%) to build the influence diagram.
when the sample size is 100, in all trials, my final Strength of Influence o Sensitiviy Analysis of each parameter get the same result.
Thanks a lot for your help!