# Estimate by babbian

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```									ENGR101 – Engineering
Technology

Decision-making
Engineers Make Decisions
cs.nott.ac.uk
Robot morphologies
http://www.cs.uml.edu/~dlipman/jsFinch/

gctronic.com                         http://www.cerebromente.org.br/n09/historia/turtles_i.htm
How to make decisions
The Wikipedia way?
Some of the decision making techniques people use in
everyday life include:
• Satisficing: Accepting the first option that seems like it
might achieve the desired result
• Acquiesce to a person in authority or an "expert", just
following orders
• Flipism: Flipping a coin, cutting a deck of playing
cards, and other random or coincidence methods
• Prayer, tarot cards, astrology, augurs, revelation, or
other forms of divination
• ...
How to make decisions
The Engineering way?
Engineers analyse problems in order to make decisions:
• Synthesis: combine the important elements into an
integrated whole.
• Analysis: using Mathematics, Science, Engineering
techniques and others (e.g. Economics) to quantify the
performance of various options.
• Communication: described the decision and how/why
• Implementation: engineers execute the consequences
of decisions.
Mathematics
Mathematics, especially statistics, are a useful tool in
understanding the likelihood of success.

Given a set of numbers:
• Mean: the average
• Median: middle of the sorted set
• Mode: most frequent

Standard deviation: square root of variance
• Expected value E  X    (ave.)
• Standard deviation
Mathematics
Mathematics, like any tool, must be used properly.

Student’s T-Test to defeat the null hypothesis.
[There is no difference in the decisions to be made]
http://serc.carleton.edu/introgeo/teachingwdata/Ttest.html
Confidence in Decisions ...

http://xkcd.com/882/
http://xkcd.com/882/
http://xkcd.com/882/
Guess versus Estimate
Guess: pulled out of thin air

“Yes, I am certain that this will work”

Estimate: prediction of the future based on past results,
research, analysis, engineering ...

“I am 90% confident based on these calculations, and
prior testing, that this may work”
Pros vs Cons
Straightforward decision-making approach

List all the features of the problem/solutions

Determine the strengths and weaknesses.

soulpancake.com
Criteria
Criteria are used to quantify solutions
• pass/fail                or
• rank based               or
• numerical                or ...

Constraining
• Soft constraint (flexible to not meet criterion)
• Hard constraint (must meet criterion)

Single vs Multiple
• Single criterion: easy to judge, but rare in real life
• Multiple criteria: trade-offs and compromises
Weighted decision-making
1.   Weight each criteria
2.   Score each option
3.   Sum up totals
4.   (adjust weights, so favoured solution wins)
Weight   Option 1    Option 2     ...
W        S     SxW   S      SxW
Cost    5        3     15    4      20
Speed   3        2     6     3      9
Lift    3        4     12    3      9
...     ...      ...   ...   ...    ...
Total                  50           45
Pareto Front
e.g. Wish to minimise the number of robot collisions (f1)
and cost (f2)

en.wikipedia.org
SWOT Analysis
•   Strength
•   Weaknesses
•   Opportunities
•   Threats

tutor2u.net
SWOT Analysis
•   Strength
•   Weaknesses
•   Opportunities
•   Threats

Widely used,
Easy to do,
Gives insight.

Political
No guarantees.                   lucidry.org
Left is good

Right is good

Let’s
compromise...

flickr.com
Go in the middle!
Compromise
As little as possible...

flickr.com

http://speedhunters.com
Or more precisely:
Anterior cingulate cortex, orbitofrontal cortex, ventromedial
prefrontal cortex
Vs
Amygdala, Hippocampus, Hypothalamus.

New ‘rational’ brain Vs Old ‘emotional’ brain

‘people who spend too much time analysing their options are
less satisfied with their decisions’
Lehrer, “The Decisive Moment”.

"They who dream by day are cognizant of many things which
escape those who dream only by night." (Edgar Allen Poe)
Decision-making gurus...

Find decision-making methods that work for you.

N.B.
If you don't like the answer that the decision-making
sheet(s) reflect back to you...
it means you haven't included all the cons
- especially the emotional ones –
or you haven't scored the factors consistently,
so re-visit the sheet(s) concerned.