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The Means-Ends Problem Solving Technique

MEA (Means-Ends Analysis) is an a approach that puts together aspects of both forward and backward reasoning in that both the condition and action portions of rules are considered when we decide which rules to apply. The logic of the process takes into account the gap between the current situation and the desired goal – where we wish to get to and proposes actions in order to close the gap between the two.

The method uses a set of rules that enable the goal to be achieved iteratively. The rules consist of two parts: rules that are prerequisites and ones that show the changes to be implemented.

MEA works by considering the present position as the current state and the objective as the goal state. The differences between the desired and the goal state are considered and actions are proposed that reduce the ‘gap’ between the initial and desired states.

Since the process is working from the current state towards a goal it is said to be doing forward chaining which implies a search strategy and a procedure that regards goal achievement as success – or if the outcome of a sub-goal is failure a new search is begun (or the process terminates as not possible).

Consider the following examples.

  1. In a travel problem the current state and the goal state are defined by physical locations where we are now and where we have to get to.
  2. In an assembly problem such as an IKEA flat pack the current state and the goal state are defined by the raw materials lying in a heap along with instructions on the floor and the finished product in your kitchen.

Aunt Agatha and the invite to tea

Aunt Agatha lives in Brighton and has invited me to tea this afternoon – she has a lot of money which she may leave to me which is actually a longer term goal for this journey. I am sitting in my office in London and need to decide how to get to Brighton.

Now there are lots of ways to do this: train, car, bus, on foot, private jet or roller blades but I subject myself to the following cost constraints:

  • I must arrive at Brighton today within three hours
  • The journey must cost no more than $100
  • Any distance less than one mile must be walked

To begin this process I consider the available means against my constraints and decide on taking the train via Victoria to Brighton. To do this I need to leave my office and travel to the main station at Victoria which is a new goal.

To get to Victoria I can walk, take a taxi, bus or go by underground. Because of time constraints and cost I decide to take the underground to Victoria – this becomes a new sub goal. The nearest tube station being less than one mile away I walk

On arrival at the station I find the line is down due to a breakdown (goal failure). I can return on foot to get my car to drive to Brighton but this moves me away from my goal on cost and distance. I decide to take the bus to Victoria which becomes a new goal and as the distance is less than one mile I walk to the bus station.

I take the bus to Victoria alight and walk to the station office and purchase a ticket to Brighton. At Brighton I have to get to Agatha’s house – I can use the Bus, Taxi or Walk. As the distance is less than one mile I walk and arrive at Aunt Agatha’s house the end goal.

Just then my cell phone rings with a message and it’s Aunt Agatha, ‘I hope you don’t mind but I forgot I have to be in London today perhaps we can make it next week…’ Arghhhhhhhh!!!

Some problems for you to solve…

Vicars and Tarts

There are 3 Vicars and 3 Tarts and a boat on one side of a river and the church on the other. How can the 6 of them get across the river for morning prayers in the boat subject to the following constraints?

  1. There must be at least one person in the boat
  2. There cannot be more than two people in the boat at any time
  3. There cannot be more Tarts than Vicars on either bank otherwise the tarts will take advantage the vicars and commit original sin.

Three coins

Three coins lie on a table in the order tails, heads, and tails. In precisely three moves make them face either all heads or all tails.

Be more critical and critique what people say

To a large extent in the academic and business world things move forward by a thorough critique of the existing body of knowledge or by taking apart the position people take on a particular issue (usually in hindsight). Often very strong positions are held based on very shaky ground and expertise claimed based on little supporting evidence. I think it is always interesting when you look at a newspaper report or an article in the trade press one can always determine the authors own position vis a vis the issue being discussed as well as the position they take in the field of knowledge they are advancing.

What we need to do when we look at a report being presented to us at work, or even on the nightly television bulletin, is to learn how to evaluate what people say and weigh the truth and merit of the argument they are proposing.

When we listen to these arguments try to assess:

  • What are the assumptions being mobilised by the author from her own perspective to support the case and what approach is being taken in the construction of the argument as far as evidence is concerned.
  • What is the purpose of the review or report – what is it for and for whom is it written?
  • What is being included or excluded from the author under scrutiny in terms of the body of knowledge and alternative views?
  • How are countervailing views dealt with and what form of words is being used to describe them – dismissive, pejorative or supportive?
  • How gaps in our understanding of the issue are explained – or are they glossed over and simplified in order to trivialise opposition?
  • What is the actual or implied call to action – what is it the writer wishes you to buy or accept that forms the core of the message?

I personally also ask – so what have you brought to the party, what contribution have you added to my understanding of this topic?

The way to read a newspaper follows the same approach – it means we engage with the author and as a consequence perhaps we will learn something. Remember we should not accept any assertions, claims, or recourses to expertise from any authors of these papers or articles unless they demonstrate their expertise with erudite argument. We need to look at all of them with a skeptical eye and try to get behind the purpose of the message and how it is aimed to persuade and orient opinion in a certain way and in business to ensure the ‘right’ decision is made.


The Ten Commandments in Risk Reduction

Risk reduction in decision making comes down to two main considerations:

Increasing our knowledge of the problem by such techniques as soft systems engineering, SODA or any of the many tools that enable us to gain a foothold on the nature of the issue and dealing with the uncertainly of the risk. Here is a simple approach that puts some rigour in our thinking when it comes to breaking down a complex problem and deciding what to do next.

There are Ten Commandments in risk reduction (Morgan & Henrion 1990)

  • Do your homework
  • Problem drives the analysis
  • Make analysis simple (but not too simple)
  • Identify all relevant assumptions (and write them down)
  • Be explicit in your decision making criteria (and write them down)
  • Be explicit in the uncertainties (and the unknown unknowns thanks to rumsfelt)
  • Do sensitivity and uncertainty analysis
  • Iteratively refine the problem statement and the analysis
  • Document clearly and completely…
    … And expose your work to peer review

If analysis can be understood it becomes more acceptable and people will buy in and have more faith in the outcome – but be careful and do not make the work over complex and avoid over simplifications as well. Both stop people making an informed decision based on what evidence you have. Also as seen above document what you do during the process that way when it goes wrong (as it often does) we can learn and move forward and get it right next time – it is particularly important to set down assumptions and what you think are ‘givens’ – these are the points that we most often get wrong.

Shark week on Discovery Channel Begins on 2nd August

Apparently when the Discovery Channel broadcasts ‘Shark Week’ which this year starts on August the 2nd visits to Florida beaches decline dramatically. Presumably, the Discovery’s programming makes the waters no less safe (I hope). However, after watching a week of kicking legs seen from a shark’s eye perspective from below, the idea of shark attack is refreshed in our minds and we choose not to offer ourselves as bait. This phenomenon is known in decision-making as the availability heuristic or bias  – a heuristic is a rule-of-thumb we apply in situations of uncertainty. What is happening is we assume that events that are easily recalled due to recency (i.e. happened last week) or that are particularly dramatic (i.e. being eaten) are more likely to occur than they otherwise do in practice. Although there is always a chance I suppose as Florida is the shark attack capital of the world and overall the USA has more shark attacks than any other country in the world due to the large amount of sharks per se, as well as being the home of the worlds three most dangerous species of shark: the Bull, Tiger and Great White as well as the culture of surfing  and water sports around its shores which puts lots of opportunity their way! Although you will be glad to hear that although shark attacks are more common in the US there are fewer fatalities than in Australia – presumably the yanks can take their foot in their hand and get the hell out of the water more quickly!

The sunnier side of the availability heuristic is the lottery and the question should you invest $2 a day in the bank (pre credit crunch) or use it to buy a lottery ticket hopefully win and move down to Florida and go shark hunting? Math makes the decision obvious I am afraid.

Suppose you invest two dollars every day (roughly $62 a month) at a reasonable rate of 10% per annum then you will take almost exactly 50 years to accumulate close to $1m (actually about $920,000 but close enough)  – so start saving now!  To earn this same $1m in a big lottery like the National Lottery in the UK, you would have to match five numbers and a bonus ball; at odds of 2,330,635-to-1 in any one game I am told. So if you spend two dollars a day for 50 years you could enter 36,500 tickets and would have 1-in-63 chance of making those million dollars. This probability of 1:63 means the expected value from the investment over the 50 years is around $16,000 – against the expected vale of $1M dollars from the investment choice – no brainer isn’t it.

However the concept of availability and the recency effect image of immediate winners enjoying extreme wealth subvert this rationality. What the crafty lottery companies do is parade in front of us some Joe who has just won a fortune and the next time we call in for gas or food at the Quickie Mart we have the faint glow in our memory that someone has just won the lottery so assume it occurs much more frequently than it does and it is our turn next. Well someone has to win surely and why not me? So we buy that ticket again and again only to tear it up with the forelorn hope of winning next time.

Here is a pic for how not to go shark fishing – I think this was off South Africa during a military training exercise.

Why men cannot think straight in the presence of an attractive woman!

I suppose many read the story the other week about research that showed men who spend even a few minutes in the company of a very attractive woman perform less well in cognitive tests designed to measure brain function. Apparently when men are intensely focused on an attractive female such is the extent that cognitive resources are used up that it is almost impossible to think of anything else – in this case one researcher could not remember his address when asked by a particularly impressively built young lady. The effect does not work the other way women I’m afraid – women are more focused on status and potential in a mate and on much more practical matters such as how much dosh she can squeeze out of the hapless jerk when they get to the divorce courts

This effect is well known in fact in the psychology self-regulation area. It is thought that the cognitive resources we have to apply to particular tasks are actually finite and get used up as we carry out tasks – particularly demanding thinking jobs at hand deplete these resources quickly. In this case the young man in question was intensely studying a potential mate and the brain power needed to do this zapped his thinking powers and blood rushed to the head and elsewhere and the thinking power simply was not available to carry out easy declarative tasks like giving her his phone number (yer dummy!). The findings have implications for the performance of men who flirt with women in the workplace or even better using attractive women in negotiating situations. When an attractive female manager is presenting the product plan and talking about market penetration there is a finite chance that her males colleagues are not thinking about marketing strategies at that moment and are thus unable to come to rational judgments about the approach. There we have it – at a stroke (forgive the pun) – the reason for the lack of seriousness given to female presenters is apparently down to innate and unalterable sexual drives due to the reproductive orientation of men when confronted with an attractive potential mate – and is not due to any socialisation process (oh no its not – this is more of your sexist claptrap ed.)

By way of balance I found this up to date picture on the functional MRI breakdown of the cognitive process in male human brain that goes a long way in explaining the key aspects of behaviour described above.


The male brain