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Agena Newsletter Number 6


AgenaRisk: Bayesian Network and Simulation Technology for Risk Analysis and Decision Support

NEW VERSION OF AGENARISK AVAILABLE

A new version (4.0.7) of AgenaRisk has been released on 15 August 2007. This new release contains new features, bug fixes and updates to the user manual and tutorials.

Changes since 4.0.6

New Features

  • Much easier configuration of risk graphs
  • All settings for risk graphs now accessible via single location in Node Properties
  • Colour changes can be saved with risk graphs
  • Confusing override check boxes removed
  • Simulation node option added to toolbar on risk map
Bug Fixes
  • Bugs fixed in cumulative plotting
  • Various bugs fixed in constant handling functionality
  • Cut and paste bugs fixed
  • No longer need to press return when entering numbers in NPTs
New Example Models
  • Advanced reliability using dynamic fault trees and reliability modelling
  • Children's birthday party decision tree
  • Business investment - flaw of averages
  • Legal uncertainty and the jury fallacy
  • Six sigma manufacturing precision
  • Normal distribution Parameter Learning

User manual

New version of user manual for AgenaRisk has been made available.

Additional information

Syed Rahman, AgenaRisk Development Team
Email: syed@agena.co.uk

Free Download

You can download the latest version of AgenaRisk here.

AGENARISK CONSULTING SERVICES

Agena offers its customers a variety of consulting services:

  • Model building, implementation and validation
  • Prototyping systems
  • Enterprise level applications development and integration services

Agena has a very agile approach to solution development which means we can remain flexible in our response to customer' needs and provide expert, customised solutions on time and within budget.

Consulting Benefits
  • True customisation of AgenaRisk for your specific business requirements;
  • Access to an experienced team with knowledge of the importance of process and methodology in building credible, efficient and scalable models
  • An experienced consultancy team which has delivered customised consulting services to clients across the globe;
  • Tight on people, time, resources? We can develop the solution - saving your company time and money;
  • Do not need to hire expensive statisticians / AI experts to implement the solution;
  • Correctly and consistently apply risk and decision analysis throughout your organisation.

To find out more about Agena's Consulting Services contact:

Ed Tranham, Commercial Director
Tel: + 44 (0) 20 7404 9722
Email: ed@agena.co.uk



The Schools League Tables Fallacy

Look at the following table showing the scores achieved by a set of schools (that we have made anonymous by using numbers rather than names). School 38 achieved a significantly higher score than the next best school, and its score is over 52% higher than the lowest ranked school, number 41.

If I told you that these were the available state schools in your local authority and that, instead of your child being awarded a place in school 38, he/she was being sent to school 41. You would be pretty upset, wouldn't you? Now scroll down to below the table.

School Number Score
38 175
43 164
44 163
25 158
31 158
47 158
11 155
23 155
48 155
40 153
7 151
30 151
6 150
9 149
33 149
19 148
10 147
12 147
32 147
2 146
27 146
42 146
28 145
35 145
49 145
45 144
46 143
1 142
18 142
22 141
26 141
4 140
14 140
29 140
39 139
8 138
5 136
17 136
34 136
3 134
24 133
36 131
37 131
15 130
21 130
16 128
13 120
20 116
41 115

In fact the numbers do not represent schools at all. They are simply the numbers used in the UK National Lottery (1 to 49). And each 'score' is the actual number of times that particular numbered ball had been drawn in the 1,172 draws of the UK National lottery that had taken place up to 17 March 2007. So the real question is: Do you believe that 38 is a 'better' number than 41? Or, making the analogy with the schools league table even more accurate, do you believe the number 38 is more likely to be drawn next time than the number 41? (after all your interpretation of the schools league table is that if your child attends the school at the top he/she will get better grades than if he/she attends the school at the bottom).

The fact is that the scores are genuinely random. Although the 'expected' number of times any one ball should have been drawn is about 144 you can see that there is a wide variation above and below this number (even though that is still the average score). What many people fail to realise is that this kind of variation is inevitable. To see why look at this explanation. If you rolled a die 60 times you would almost certainly not get each of the 6 numbers coming up 10 times. You might get 16 threes and only 6 fours. This does that not make the number three better than the number four. The more times you roll the die, the closer in relative terms will be the frequencies of each number (specifically, if you roll the die n times the frequency of each number will get closer and closer to n divided by 6 as n gets bigger); but in absolute terms the frequencies will not be exactly the same. There will inevitably be some numbers with a higher count than others. And one number will be at the 'top' of the table while another will be 'bottom'.

I am not suggesting that all schools league tables are purely random like this. But, imagine that you had a set of genuinely equal schools and you ranked them according to a suitable criteria like average GCSE results. Then in any given year you would expect to see a wide variation like the table above. And you would be completely wrong to assume that the school at the top was any better than the school at the bottom.

Contact Us:

E: newsletter@agena.co.uk

Agena Limited
32-33 Hatton Garden
London
EC1N 8DL
Tel: + 44 (0) 20 7404 9722
Fax: + 44 (0) 870 1318460


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