Monday, June 4, 2018

Project scheduling with Monte Carlo simulation on mobile

Uncertainty is a common situation in project scheduling. It happens because we lack 
experience from doing some activities before or have some uncontrollable factors on 
the project. The classic technique we normally use is PERT (Program Evaluation and 
Review Technique). But there are some drawbacks with this technique especially when 
project has activities which are nearly equal in duration and also run in parallel. Nowadays 
the technique that should be used is Monte Carlo simulation. However using simulation 
requires at least desktop computer for constructing network model and experimenting 
with it. Microsoft Project can help us constructing network model. But we need  another 
special software for performing simulation with Microsoft Excel, e.g., RiskAMP, @Risk
or without Microsoft Excel, e.g., Full Monte. In this article we will show you the way easier 
by using AlmanacSoft SchemeSim app. Only one app for doing all these steps and also 
on mobile device.

What is AlmanacSoft SchemeSim (ASS)
ASS is android app that performs Monte Carlo simulation for project scheduling. It answers 
three important questions: firstly, when project will be completed, secondly, when each 
activity will start and end, and finally, the critical probability for each activity in the project. 
ASS automatically creates network model and do simulation within one step and produces 
scheduling report as an output. ASS supports two types of random generating for activity 
durations: Triangular and Pert distribution. It detects how many CPU core the mobile has 
and uses all of them for parallel native simulation. That is necessary because mobile has 
limited resource. To perform simulation efficiently needs high performance computing by 
creating native (binary) code and run it in concurrency. ASS also supports calendar time 
and working day and time. That means we can specify which day in a week we actually 
work, e.g., Monday to Friday,  and in which time interval, e.g., 8:30 - 16:30.

ASS overview and installation
ASS can be download and install from google play store. ASS offers in-app purchases. 
That means by default this app is in basic edition and can be upgraded to professional 
edition by paying subscription fee. In basic edition it can work for free with project not 
more than five activities. You also have a free trial period for 30 days after upgrading to 
professional edition. During this trial period, if you don’t satisfy with it you can cancel 
subscription with no charge.

When you open the app you will see this following screen. This is the Input page for 
type in your project data. 

There are other two pages, e.g., Report and About, you can navigate to them when you tap on three line menu. After simulation has finished, report will be generated in Report page.


 Project data preparation

You have to prepare project data as table above before inputing. In this case our project consists of 5 activities. We estimate activity duration by using three-point estimating (a = the best-case, 
b = the worst-case, m = the most likely) which a <= m <= b. We also analyze for predecessor of each activity.

Entering data

Type in number of activities (5) and click add button.

If you type wrong, you can check the box on the right upper side of each activity and click remove button, If you want to add more activities, you can do it again as many as you want. Type in activity name, distribution, a, b, m and predecessor. For distribution you can choose Triangular or Pert distribution. If you have no experience of this activity before, choose Triangular is better. But if you have it,  Pert distribution is better. If you have predecessor more than one activities, type activity name separated by comma with no space.

Now select project start date and time by click the right button. If you don't select it will use current date & time as a project starting point. In this case I choose 1 October this year and at 9 AM.
For confidence level, I choose 99% and use 100,000 iterations for simulation.

Simulation and report generation
You can save input file by click on three dot menu and select save input file for later use. Now it is time to perform simulation, click on the pink button and click run.

This project will take 20.258 days with confidence level 99% and will be finished on Sun, 21 October 2018 at 11:29. There are also detail of starting and ending date&time for each activity. Activity d is the most critical with probability 97.604% and the lowest critical is activity e which is 2.396%. You can see that we use just only 2.07 seconds for 100,000 iterations.

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