Unit 8 Design Decisions: How can I make better design decisions?

1. Factor of Safety
- used to offset the potential effects of unknown variables by adding new elements to its construction or system to prevent system failure.
- A new designs must have large factors of safety to overcome the large number of unknown.

Example:
There is a factor of safety in a power bank. As you can see there are two USB ports, one with 1.5A and another 2.1A which is suppose to indicate which port is suppose to be used on what gadget. 1.5A are used to charge phones while 2.1A are usually for bigger gadgets like an ipad. However, it will not cause any incident even if you attach the gadgets to the wrong port.

2. Redundancy
- The use of more elements in a design to maintain its performance if one or more elements fail to perform.
- Four types of redundancy
a) Diverse redundancy - One function has many elements of different types.

From the picture above, we can see that the laptop is having diverse redundancy where it has two source of power supply to the laptop computer. The power source on the left, is the A/C power source for the laptop and on the laptop itself, it has a dry cell battery for the power supply. 

b) Homogenous redundancy - multiple elements of a single type

The badminton racket is made up of multiple elements. So if one of the element has break, then the racket cannot been used already.

c) Active redundancy - Provide several independent supports to a element

From the picture above, The tyre needs four screws to support. However, the car still can function even if one of the screw of the tyre is missing. 

d) Passive redundancy -  Provide support when active redundancy fails

If one of the strap of the handbag has break, the other strip still can support the handbag.

3. Flexibility-Usability Tradeoff
- the usability of a system decreases as flexibility of a system increases
- flexible design perform more functions but less efficiently because it more complex and difficult to use.

Example: 

The brown color car remote control has more function but it more complex (flexibility increase, usability decrease)  when compare to the grey color car remote control.

4. Satisficing
- It is better to achieve a satisfying design rather than an optimal design
- it is a type of cognitive heuristic that quickly meet human needs.

Example: 

The example above shows the website designer has create satisficing function for user. This is a online shopping store where the sorting function of the store shows satisficing, where user could click on the function and quickly determine the item they want to satisfy their needs. It may not show the best, but it could solve the problem by satisfying user needs.

5. Ockham's Razor
- simplicity is preferred to complexity in a design
- unnecessary elements decrease design's efficiency and have probability to creates problems

Example:

In this phone screen interface, it shows simplicity where it cut off unnecessary design and only focus on a few main function that user always use and with label below each icon. It is simple and easy to access. 

6. Form Follows Function
- can be interpreted in 2 ways
a) descriptive interpretation - based on the belief that form follows function in nature. The outlook of an object should be primarily based on its intended function.
b) prescriptive interpretation - functional consideration is primary consideration while aesthetic consideration is second consideration in a design

Example:
This clothes hanger does not has high aesthetic value but it does fulfill the function that it was designed for. Hence, it shows form follow function.