Posts by Oskar

    Re: Interpolate An Array Of Numbers


    Hi!


    There are many ways to interpolate!


    Do you know anything about your data? In example, is it usually linear, or maybe logarithmic?
    If it is, you can plot your data and add a trend line. Display equation on chart, and there you have your interpolated function. Either type in this formula manually to calculate missing points, or, to get acces to the trend line formula, try looking into LINEST or LOGEST functions. With this formula, you can calculate the missing points so that they "fit" your data.


    Also, interpolating between every point in the array has been delt with earlier, ex http://www.ozgrid.com/forum/showthread.php?t=69973

    Re: Macro To Plot x & y Coordinates & Create Inverse Y-Axis?


    Sure, you could do it manually by clicking the axis and selecting crosses at maximum and reverse plot order. Here is how to do it with a macro...

    Code
    With ActiveChart.Axes(xlValue)
            .Crosses = xlMaximum
            .ReversePlotOrder = True
    End With

    Re: Optimal Combination Model With Constraints & Variables


    Let me try to explain with an example:


    If you ask 1% of the population what they will vote, is then the result representative for forecasting the result in the acctual election with 100% of the population? There probably is some mathematics behinds this, maybe you can find some more information from Palisade/ risk.


    A quick and dirty way of determining whether it is representative or not is the following:


    1. ask 1 % of the population
    2. ask another 1% of the population
    3. Compare 1 and 2; if they agree, then 1% is enough, if they are very different, then you must ask a larger % of the population. So if you have time, run the 1% case a few times and compare. Error tolerance depends on the problem...


    risk tip: Is it not also possible to look at a distribution of the choosen samples? This way, you can tell wether the 1% samples choosen spans the whole posible sample space, thereby "represents" possible outcomes.

    Re: Representative Sample


    Hi!


    There might be some mathematically way of calculating what is the minimum number of samples you need.


    However, one way of determning it is to run the "simulation" a few times with, lets say, with 1% of the possible samples. How much does your answer change? If it changes only a "litle", then it is enough, if it changes "alot", then it is to few... So, whats litle/alot depends on the problem