Reviewing the simulation results in Tamara

When the simulation is complete, Tamara will show a window like this:

On the left of the screen each parent and child task is listed. By default, the Level 0 task (entire project) is selected at the end of the simulation run. You can select any task or sub-task from this list.

In the middle will appear a plot related to the selected task, and to its right some basic statistics relating to the plot. At the end of a simulation, Tamara shows a histogram of the finish date of the entire project by default.

You can change the graph to be displayed by selecting from one of the icons in the View group in the ribbon at the top of the screen:

You can choose to show the start date, finish date, duration or total costs of a task by selecting one of the icons in the Type group in the ribbon:

The start and finish dates take account of any project calendars that were specified in the original Primavera or Project schedule model, and will usually therefore show gaps in the histogram for weekends when the scaling used is days.

The scaling of the horizontal axis can be changed by selecting one of the icons in the Step group in the ribbon:

Tamara offers ten different plots of the simulation results, described below. They are:

The ribbon controlling how the plot is presented changes depending on the type of plot selected.

Histogram plot

The ribbon shown with the Histogram plot is as follows:

The histogram plot shows the duration, start date, finish date or cost of the selected task on the horizontal axis and the probability of that duration (or date) occurring on the vertical axis. For example, the following plot shows the duration of the task ‘Detail, fabricate and deliver steel’ project:

The histogram plot is a useful visualization for the range of durations (between 55 and 75) and the most likely (64 days).

The vertical axis is labelled ‘Probability density’, which is the technically correct term to use, because the probability is actually the area under this curve. However, for practical purposes you can just think of it as the probability of the horizontal axis value occurring. The most frequent simulated value is at 64 days, which is the tallest bar towards the middle of the plot. The bar’s height of about 0.1 (or 10%) shows the fraction of the simulation data that rounded to 64 days. We can summarize this as saying ‘There’s a 10% chance the task will take 61 days’. The probabilities (sum of the histogram bar heights) sum to 100%.

Note:  one can read from the plot that there is a 10% chance the task will take 64 days. One should be careful when using such expressions. People who are somewhat unfamiliar with probability concepts will often say something like there is a 50% chance the project will take 120 days, when what they really mean is there is a 50% chance the project will take less than 120 days.

Cumulative ascending plot

The cumulative ascending plot (sometimes known as an S-plot) shows the duration (or date) on the horizontal axis and the probability of falling below that duration (or date) on the vertical axis. For example, the following plot shows the finish date for the example model ‘Parallel correlation example’:

The plot shows that this project has about a 20% probability of finishing before 26 Oct 2018. By hovering over the plot with your mouse you can see the probability more precisely for any specific date, for example:

which shows that there is a 64% probability that the task will finish before 10 Nov 2018.

Cumulative descending plot

The cumulative descending plot shows the duration (or date) on the horizontal axis and the probability of falling above that duration (or date) on the vertical axis. For example:

 

Pareto plot

The ribbon shown with the Pareto plot is as follows:

The Pareto plot is a combination of the Histogram and cumulative ascending plots. The horizontal axis shows the duration (or date). The left vertical axis shows the scaling for the histogram plot, and the right vertical axis shows the scaling for the cumulative ascending plot. Hovering over the plot with the mouse will allow you to read off both scales:

 

Tornado plot

A Tornado plot illustrates the sensitivity of the output of a selected task to the other variables in the model. Select a task, a property (start, finish, duration, cost) and click the Tornado icon.

The length of the bar (in days) represents the difference, on average, in the property of the selected parent task between when each influencing uncertain component in the model (either a child, a risk event, a task that may or may not occur, or a risk factor) is at a very low or a very high value. Thus, the longer the bar, the greater the influence of the model component. Tamara automatically filters out and plots the most influential among them, according to the number of bars selected in the ribbon control and the number of levels that Tamara is instructed to drill down:

The Tasks, Risk Events, Risk existence and (Productivity) Risk factors icons toggle on and off when clicked. Clicking Tasks on and Risk Events off, for example, will display the sensitivity of the parent task to child task durations alone:

Conversely, clicking Tasks off and Risk Factors on will display the sensitivity of the parent task to risk events alone:

Clicking everything on will display the sensitivity of the parent task to child task durations in blue and risk events and factors in red:

Periodic cashflow

The periodic cashflow plot allows you to see the amount of money that is projected to be spent during each period of the project for any selected task or summary level. . To view, select Trend from the view options, and Periodic from the Trend options. The period can be switched between different periodic lengths (days, weeks, etc) in the Cost Summation Period part of the ribbon:

Cumulative cashflow

The cumulative cashflow plot allows you to see the total amount of money that is projected to be spent up to and including specific dates for any selected task or summary level. . To view, select Trend from the view options, and Cumulative from the Trend options. The time between each measurement date can be altered (days, weeks, etc) in the Cost Summation Period part of the ribbon:

Finish date - total cost scatter plot

It is also possible to plot a scatter plot of the finish date and related cost - again, for any selected task or summary level. In the following examples, the plots show the cost and time for the Electrical part of the project. There are two options:

Option 1: Scatter plot with a trend line

This plots the total cost and finish dates together, and draws a line showing the mean cost accumulated during each period:

 

 

To view, select Trend from the view options, Scatter from the Trend options, and ensure that the Show Trend Line option is ticked in the Scatter Options section of the ribbon. The period can be switched between different periodic lengths (days, weeks, etc) in the Cost Summation Period part of the ribbon.

 

Option 2: Scatter plot without a trend line

This plots the total cost and finish dates together:

 

 

To view, select Trend from the view options, Scatter from the Trend options, and ensure that the Show Trend Line option is unticked in the Scatter Options section of the ribbon.

Stochastic Gantt chart

You can also see a Gantt chart with information showing the uncertainty about when each task will start and finish. Click the Stochastic Gantt tab. On the left is a collapsible list of the tasks, by default aggregated to level 1. On the right box plots show the range of dates each task will start and finish. Hovering over the task with the mouse makes a pop-up appear with detailed information. The following plots shows a stochastic Gantt chart with finish dates only, for a selected number of tasks:

The Outer and Inner Envelope parameters allow you to specify the probability ranges that are shown in the box plot. For example, by selecting 5% for the outer envelope, the box plot arms will extend out to the P05 and P95 values. Selecting 25% for the inner envelope, the red box (inner envelope) will cover the P25 to 75 range. A tooltip pops up when hovering over each plot, showing which percentiles are plotted and their values (see above).

 

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