goms analysis on the back of the envelope
DESCRIPTION
The GOMS keystroke level model is a simple technique that allows you to quantitatively compare the efficiency of alternative designs. Its powerful, compelling and can be done in a few minutes yet most UX professionals have never heard of it.TRANSCRIPT
GOMS analysis
On the back of the envelope
GOMS
Is not a venereal disease...
GOMS
It is a simple technique for quantitatively
comparing the efficiency of designs
BTW… when I say GOMS I mean
GOMS keystroke level Model
(KLM or KLM-GOMS)
Use it in conjunction with your
qualitative tools
+
You'll need the following tools
+ +
A quick story...
Deutsche Bank Trading Floor
London 2011
Numbers are compelling
There are 3 reasons you might want to use
GOMS analysis:
1. Speed matters
2. You need to convince stakeholders
3. You want to become a better designer
When to use GOMS
The premise
The time taken to perform a task is the sum of
the time it takes to perform the elementary
gestures that make up that task
The steps
1. Define the task
2. Break it down into its gestures
3. Apply mental operators
4. Add up the numbers
1. Define the task
KLM models the interaction of an experienced
user doing a defined task.
2. Break it down into its gestures
KLM has a basic set of gestures; each with a
typical time assigned to it - which is sufficient
for comparative analyses.
2. Break it down into its gestures
Keying (K)
= 0.2 sec
2. Break it down into its gestures
Pointing (P)
= 1.1 sec
2. Break it down into its gestures
Homing (H)
= 0.4 sec
2. Break it down into its gestures
Mentally preparing (M)
= 1.35 sec
2. Break it down into its gestures
Responding (R)
= n sec
3. Apply mental operators
The hardest part of KLM. But it all comes down
to chunking.
M +
Chunk Chunk Chunk
Chunk M + Chunk M + Chunk
Gestures
3. Apply mental operators
HPK M +
KKKKKKKKKKKKKKK Helen of Troy:
356.34:
M +
KKKKKK M +
KLM: K M + K M + K M +
4. Add up the numbers
HMPK
0.4 + 1.35 + 1.1 + 0.2
3.05 sec =
Example: Date of birth
What's your pet way of collecting date of birth?
Facebook:
Yahoo:
Single masked
input field:
Facebook: 3 drop-downs
Click on month, select 'July'
MPK MPK
Click day, select '11'
MPK MPK
21 sec
Click year, scroll, wait, mouse off
MPK MP R MP (where R=1.0)
Select '1980'
MPK
Yahoo: Input, drop-down, input
Click day, type '11'
MPK HMKK
Click month, select 'July'
HMPK MPK
15.7 sec
Click year, type '1980'
MPK HMKKKK
Single masked input field
Click field, type '11'
MPK HMKK
Type '07'
MKK
8.7 sec
Type '1980'
MKKKK
Date of birth results
Single masked input field ~2.5 times faster!
21 sec
15.7 sec
8.7 sec
Happy GOMSing
You now know enough to start using KLM-
GOMS on your projects!
For more guidance I recommend Jef Raskin’s
“The Humane Interface”
Thanks!
@AndrewUX
designthinkage.com