Ventana software support forum

Dear Tom, Karan and LAUJJL,

thanks for your explanations. i will study more on the optimization.

cheers,
adjie

Dear Forum, i am doing sensitivity test on my model. i change one variable in each simulation. for example, i increase the variable by 10%. from the simulation results, i want to rank the changed variables in terms of their sensitivity to the simulation results. i plan to make a categorization on hi...

Thanks tony and tom for your suggestion. i apply tony's mechanism in my model. it is working. and i think, the mechanism also count the last time step. But, i still have no idea in applying tom's suggestion in my model. i tried to look for :MACRO: function in vensim, but i did not find it. can you g...

Dear All, i have a question about how can i calculate the result of simulation by numbers of week. for example, in sample model (as attached), i simulate the model resulting rainfall pattern over 1000 weeks. what i want to do is to calculate the number of weeks for the rainfall which has more than 0...

thanks for your responses. i attach the process of making sensitivity test in operasion in the sample file.docx . and, i get the negative result in iteration 1595. the negative value is not correct since i set the minimum value of 0.001in the formula. sorry, i can not attach the result as it is too ...

Dear All, i try to make a simple model with just only two variable (rainfall and noise seed), sample.mdl . i use formula of RANDOM WEIBULL( 0.001, 0.023625, 0.962, 0, 1, 0). when i simulate the model, it looks good. But then, i do the sensitivity analysis with the parameter of noise seed from 1 to 1...

Thanks tom,

i think, 0.01 is a constanta. so, every results of lognormal random analysis will be added with 0.01. and the numbers within the bracket are Logmean= 0.0453
Logstd = 0.0205.

cheers!

Dear All, i tried to do sensitivity analysis on my rainfall data. i did several times for the iterations of; 50, 100, 500,600 and 1000. when i did the 50 iteration, the rainfall data is ok. but when i did the 100 iterations, the data in 90th looks invalid. this problem also occur when i did 100, 500...

i try the formula of: myLogNorm = geometricMean*EXP( geometricSD*RANDOM NORMAL(-6,6,0,1,0) ), but it seems not working. actually from the statistical analysis, i have formulas in representing my data as follows; 1. Distribution: Lognormal 2. Expression: 0.01 + LOGN(0.0453, 0.0205) Logmean= 0.0453 Lo...

Dear All, i have another problem on random distribution. i have a log normal distribution. since the log normal distribution is the same as EXP of random normal. i tried to use the formula of EXP(RANDOM NORMAL( {min} , {max} , {mean} , {stdev} , {seed} )). but, when i run the model, the model gives ...

Thanks Tomfid,

i tried your suggestions several time on my model just now. it seems working. thanks a lot and sorry for the late response. i just get back to work again.

thanks,

Right !! Thanks for your answer. what about others, like;
O = order = ??
(random binomial) P = ??
(random poisson) M= ??
(random weibull) S =??
N = numbers of trial = ??

cheers,

no worries. thanks for your reply. yes, i have seen that page. but, sorry, i can not define those terms into specific numbers from that pages except some of the terms (as i mentioned in my first massage). so that, i can not make the random formula. oh ya, from that page, i can also see that if the d...

Dear Forum, i have some problems in understanding the terms in random distribution. within the vensim manual, i can find some of the terms differently than in statistics' software such as arean5. i define my data distribution by using arena5. so that, i have to match the terminologies in random dist...

thanks for both of you (adminstrator and tom). i have sent the file to the administrator and have an adequate feedback. thanks a lot

sorry i miss some thing. i prefer to send the model to your private email rather than to the forum.

yes. can i ask your email address? i prefer to go to the private rather than forum.

thanks for your help.

thanks for your kind helps. but, i am still have this issue after following your suggestions. i have changed the seed from 0 to a variable called seed. then i put 1 for the value of seed (as a control variable). but, the results make no different. there is inconsistency on the results. for example o...

Dear administrator, thanks for your prompt response. but, i have some further questions. how can i make the NOISE SEED. so far, i use random normal formula. and the seed is the default value from the software. it is 0. if yes, when i want to compare between several simulations with some changes on t...

Dear all, sorry my previous massage is in welcome and general information section. the massage is the same as before, that is; i do really need some helps from the forum. i use several random formulas in my model. when i simulate the model, i think, the model will pick different values in random for...

thanks for your prompt response. i attach the simple version of my model in doing sensitivity analysis. may be i ask the basic line of doing the sensitivity analysis in vensim. what do i need to do in making sensitivity simulation on vensim? at this stage, i take a case as on attachment. for example...

hi, i am having a problem in making sensitivity simulations. what i do was: i click the button of start sensitivity simulation. then, i select one of my controller variable (lets says percentage of forest areas). i make intuitive value for minimum and maximum. then when i click finish button, the mo...