what is Scrum poker ?

Scrum poker help a scrum team to underhand the complexity of each task and estimate the time that they need to do it.

what are the methods of estimation ?

• Numeric sizing (1 to 10)
• T-shirt sizing (XS to XXXL)
• Fibonacci sequence (1,2,3,5 to 89, Coffee Time to think more about it !)
• even dog breeds sizes ! (Chihuahua  to Great Dane)
• more details

Why Fibonacci is better ?

• the first and the most important reason is ” Its cool ! “
• as the number increase the level of uncertainly increase and that remind you to break down a task [more detail]
• larger gaps between people estimation help to understand the level of uncertainly [more detail]

A quick example

1. what is the size of your phone in centimeter ? [numeric :1] [T-shirt :XS] [Fibonacci :1]
2. what is the size of your desk in centimeter ? [numeric :2]  [T-shirt :S] [Fibonacci :2]
3. what is the distance between your desk to front door in centimeter ?[numeric :4]  [T-shirt :M]  [Fibonacci :13]
4. what is the distance between your desk and your house door in centimeter ? [T-shirt :L] [Fibonacci :21]
5. what is the distance between your house to Pizza tower ?! [numeric :1000] [T-shirt :XXXL][Fibonacci : Coffee !]

conclusion

basically you should revise when your level of uncertainly increase or you are not sure about the complexity of the task  and Fibonacci give you a better feeling to choose a right task to break down .

In my opinion the best way of Scrum poker is use Chris Sims method and order the task from easy to hard and then try to assign complexity number with Fibonacci algorithm.