{"id":505,"date":"2024-03-14T05:27:03","date_gmt":"2024-03-14T05:27:03","guid":{"rendered":"https:\/\/sites.rutgers.edu\/yasai\/?page_id=505"},"modified":"2024-05-07T13:10:38","modified_gmt":"2024-05-07T13:10:38","slug":"user-guide","status":"publish","type":"page","link":"https:\/\/sites.rutgers.edu\/yasai\/user-guide\/","title":{"rendered":"User Guide"},"content":{"rendered":"
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Version 3.0 User Guide<\/h1>\n

Jonathan Eckstein, with assistance from Sohum Sanghvi<\/h3>\n

June 2019 (Security Detail Updates October 2022)<\/h3>\n
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 <\/p>\n

About Yasai<\/h3>\n

The YASAI.XLA add-in is intended is intended for teaching elementary Monte Carlo simulation. It does not provide all of the functionality of @Risk<\/a>, Crystal Ball<\/a>, and other commercial products, but should be sufficient for teaching purposes.\u00a0 It also has some features that commercial produces lack.\u00a0 A key advantage is that YASAI.XLA consists of a single downloadable file that can be run on any PC or Mac with a recent version of Excel, without requiring administrator privileges. It is also designed to be very straightforward to use. In exchange for this simplicity, YASAI may run simulations slower than commercial products, since all the random number generation code is interpreted in Visual Basic.<\/p>\n

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 <\/p>\n

Downloading and Installing Yasai<\/h3>\n

Downloading (All Browsers and Operating Systems)<\/strong><\/p>\n

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  1. Download the YASAI.XLA file from the “Downloads” page on the YASAI website<\/a>.\u00a0 Do not let your browser open the file directly in Excel. <\/strong>\u00a0Instead simply save the file somewhere convenient (the default folder is usually “Downloads”)<\/li>\n
  2. Some browsers may rename the YASAI.XLA file to YASAI.XLS.\u00a0 If this occurs, manually change the name back to YASAI.XLA before proceeding with the remainder of these instructions.<\/li>\n
  3. If necessary, move the YASAI.XLA file to some location where you will not inadvertently delete it.<\/li>\n<\/ol>\n


    \nSecurity Policy Adjustments<\/strong><\/p>\n

    Excel has become increasingly security minded over the years.\u00a0 Before attempting to install YASAI, please make the following adjustments.\u00a0 The following directions are for Windows, but the procedure for Macs should be similar.<\/p>\n

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    1. Launch Excel.<\/li>\n
    2. Click the “FILE” tab above the ribbon.<\/li>\n
    3. Click the “Options” button at the lower left of the window.<\/li>\n
    4. Click “Trust Center” on the left of the resulting Options dialog box.<\/li>\n
    5. Click the “Trust Center Settings…” button.<\/li>\n
    6. If this option is available, select “Trusted Locations” on the left panel (if this option is not available, skip to step 9)<\/li>\n
    7. Click the “Add New Location…” button.<\/li>\n
    8. In the resulting dialog box, enter or browse to the location of the folder containing YASAI.XLA, and click “OK”.<\/li>\n
    9. Click “Macro Settings” on the left panel.<\/li>\n
    10. Check “Trust access to the VBA project object model”<\/li>\n
    11. Optionally, click the radio button for “Enable VBA macros (not recommended…) — in principle, it should not be necessary, but sometimes appears to be.<\/li>\n
    12. Click “OK”.<\/li>\n<\/ol>\n


      \nInstallation for Windows Excel 2013\/2016\/365<\/strong><\/p>\n

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      1. Launch Excel.<\/li>\n
      2. Perform the security policy adjustments listed above.<\/li>\n
      3. Click the “FILE” tab above the ribbon.<\/li>\n
      4. Click the “Options” button at the lower left of the window.<\/li>\n
      5. Click “Add-Ins” on the left of the resulting Options dialog box.<\/li>\n
      6. Select “Excel Add-Ins” in the pull-down menu at the bottom of the dialog box, and then push the adjacent “Go…” button.<\/li>\n
      7. You will now be at the “Add-Ins” dialog box (the add-in manager).<\/li>\n
      8. Click the “Browse” in the resulting dialog box, locate the YASAI.XLA file you saved, select it, and click “OK”.<\/li>\n
      9. Select “OK” to exit the add-in manager.<\/li>\n<\/ol>\n

        YASAI should now be loaded.\u00a0 An “Add-Ins” pane should appear in the ribbon interface.\u00a0 On this pane, there should be a button labeled “YASAI”.\u00a0 If you click it,several options should appear, starting with “Simulation…”.\u00a0 If the currently visible Excel object is a chart rather than a worksheet, the first option in the YASAI button should instead be “Charts…” and there will be only two options.<\/p>\n

        Installation procedures for older versions Windows Excel are generally similar.\u00a0 You find the add-in manager and then browse to find YASAI.XLA.<\/p>\n

        Installation for Mac Excel 2011<\/strong><\/p>\n

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        1. Launch Excel<\/li>\n
        2. From the “Tools” menu in the menu bar, select “Add-Ins”<\/li>\n
        3. The add-in manager dialog box should appear.\u00a0 Click “Select”, locate the YASAI.XLA file you saved, select it, and click “OK”.<\/li>\n
        4. Click “OK” to exit the add-in manager.<\/li>\n<\/ol>\n

          YASAI should now be loaded.\u00a0 A new menu “YASAI” should appear in the menu bar, with the options “Simulation…”, “Charts…”, and so forth.\u00a0 If the currently visible Excel object is a chart rather than a worksheet, the first option in the YASAI button should instead be “Charts…” and there will be only two options.<\/p>\n

          Installation for Mac Excel 2016<\/strong><\/p>\n

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          1. Launch Excel<\/li>\n
          2. From the “Tools” menu in the menu bar, select “Excel Add-Ins”<\/li>\n
          3. The add-in manager dialog box should appear.\u00a0 Click “Browse”, locate the YASAI.XLA file you saved, select it, and click “OK”.<\/li>\n
          4. Click “OK” to exit the add-in manager.<\/li>\n<\/ol>\n

            YASAI should now be loaded.\u00a0 However, its options may not appear until you open a new workbook.\u00a0 The next time you open a workbook, you should see an “Add-Ins” pane in its ribbon.\u00a0 Within this pane should be five new popup buttons, the first of which should be “YASAI_Simulation”.\u00a0 If the currently visible Excel object is a chart rather than a worksheet, there should be only two new buttons, the first of which should be “YASAI_Charts” and there will be only two options.<\/p>\n

            Upgrading from Earlier versions of YASAI<\/strong><\/p>\n

            If you are upgrading from an earlier version of YASAI, just follow the same installation instructions above.\u00a0 After selecting the YASAI.XLA file in the add-in manager and clicking “OK”, you may see a message that “a file with the same already exists in the same location” and asking whether you wish to replace it.\u00a0 Click “Yes”.<\/p>\n

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             <\/p>\n

            YASAI Functions for Generating Random Variables<\/h3>\n

            YASAI provides Excel functions that return random numbers with specified distributions. They will generally return different, randomly chosen values every time you recalculate a spreadsheet. The currently available random number generation functions are:<\/p>\n

            GENUNIFORM<\/strong> (a<\/i>, b<\/i>): Both arguments are numbers. Normally, it is expected that a<\/i> < b<\/i>. If so, a random number uniformly distributed over the interval [a<\/i>, b<\/i>)\u00a0 — that is, x<\/i> such that a<\/i> <<\/u> x<\/i> < b<\/i> — is returned. If a<\/i> = b<\/i>, then the value a<\/i> (or equivalently b<\/i>) is returned. If a<\/i> > b<\/i>, an error value is returned.<\/p>\n

            GENNORMAL<\/strong> (m<\/i>, s<\/i>): Both arguments are numbers. If s<\/i> < 0, an error value is returned. If s<\/i> is zero, the return value is m<\/i>. Otherwise, a random value with a normal distribution with mean m<\/i> and standard deviation s<\/i> is returned.<\/p>\n

            GENBINOMIAL<\/strong> (n<\/i>, p<\/i>): The first argument n<\/i> must be a nonnegative integer, and the second argument p<\/i> must be a number in the range [0, 1]. Otherwise, an error value is returned. If these conditions are met, then the return value is an integer drawn randomly from a binomial distribution with n<\/i> trials and probability p<\/i> of success at each trial. If n<\/i> = 0, then the return value is always 0. The implementation is efficient even when n is large.<\/p>\n

            GENPOISSON<\/strong> (m<\/i>): The argument m<\/i> is a nonnegative number. A negative argument causes an error value to be returned. A zero argument causes zero to be returned. Otherwise, the return value is randomly chosen from a Poisson distribution with mean value m<\/i>. The implementation is efficient even when m is large.<\/p>\n

            GENTABLE<\/strong> (V<\/i>, P<\/i>): The arguments V<\/i> and P<\/i> are blocks of cells or lists (an example of a list is “{1,3,7}”) having the same number of cells.\u00a0 Essentially, the function returns each value in V<\/i> with the probability specified by the corresponding element in P<\/i>.\u00a0 If the two arguments have the same number of cells but differing numbers of rows and columns, the correspondence is determined by scanning first across the first row, then across the second row, and so forth.\u00a0 Non-numeric entries in P<\/i> are treated as if they were zero.\u00a0 If the two arguments do not have the same number of cells, or if P<\/i> contains any negative numbers, or if P<\/i> contains only zeroes, an error value is returned.\u00a0 If the values in P<\/i> do not sum to 1, they are rescaled proportionally so that they do.\u00a0 For example, GENTABLE({1,2,3},{.2,.5,.3}) returns 1 with probability 0.2, 2 with probability 0.5, and 3 with probability 0.3.<\/p>\n

            GENEXPON<\/strong> (a<\/i>): The argument must be a positive number, or an error value is returned. If the argument is positive, the return value is randomly chosen from an exponential distribution with mean value 1\/a<\/i>.<\/p>\n

            GENGEOMETRIC<\/strong> (p<\/i>):\u00a0 Returns a geometric random variables with a probability p<\/i> of being 1.\u00a0 This variable is equal to the number of trials of a mean p<\/i> Bernoulli (or equivalently, GENBINOMIAL(1,p<\/i>)) variable until the value 1 is obtained.\u00a0 The value of p<\/i> must be greater than 0 and less than or equal to 1, or an error value is returned.<\/p>\n

            GENTRIANGULAR<\/strong> (a, b, c<\/i>):\u00a0 Returns a value from a triangular distribution with minimum a<\/i>, mode b<\/i>, and maximum c<\/i>.\u00a0 The arguments must be numbers with the property a<\/i> <<\/u> b<\/i> <<\/u> c<\/i>, or an error value is returned.<\/p>\n

            GENLOGNORMAL<\/strong> (m<\/i>, s<\/i>): Generates a lognormal random variable, and is equivalent to exp(GenNormal(m<\/em>, s<\/em>)).\u00a0 The restrictions on the arguments are the same as for GENNORMAL.<\/p>\n

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             <\/p>\n

            Specifying Scenarios<\/h3>\n

            In YASAI, decision variables are called parameters<\/em>.\u00a0 For each possible value combination for the parameters, YASAI obtains a sample, recording the values of all the output variables.\u00a0\u00a0 YASAI provides the function SIMPARAMETER(L<\/i>, name, <\/i>group<\/em>) to specify each parameter:<\/p>\n