Sprint Planning Estimation

1. As fellow team members, don't they have an interest in understanding each other's perspective?

2. The topics to be addressed seem clear. Why constrain the event with an agenda at all?

3. If the team lacks members, do they have the skills needed to plan and complete a Done increment in the first place?

1. As fellow team members, don't they have an interest in understanding each other's perspective? -> I agreed with you all members in the team join together estimation sprint backlog

2. The topics to be addressed seem clear. Why constrain the event with an agenda at all? -> I think that any meeting should specific agenda in order to all members in scrum team understand purpose, schedule of the meeting. If you have any ideas or experiences in create sprint planning effectively, please sharing knowledge about that

3. If the team lacks members, do they have the skills needed to plan and complete a Done increment in the first place?-> sorry, my question is incorrect, i mean that the member in development team was absence in the sprint planning, what should development team do?

 I think that any meeting should specific agenda in order to all members in scrum team understand purpose, schedule of the meeting.

I'd suggest that the Scrum Guide makes the purpose of Sprint Planning clear, and that perhaps there ought to be no schedule at all. 

the member in development team was absence in the sprint planning, what should development team do?

Are they satisfied that the team member is fully committed to the team? What was the reason for absence, and can the team cope until that member is available as required?

As fellow team members, don't they have an interest in understanding each other's perspective? -> I agreed with you all members in the team join together estimation sprint backlog

What Ian was implying is that the team should want to be cross-functional, so that each of them are "T" shaped instead of "I" shaped when it comes to knowledge and expertise. 

I think that any meeting should specific agenda ...

Does the Scrum Guide present Sprint Planning as a meeting?  Doesn't it present it as an event?  While events can sometimes have schedules they also can be freeform times for people to gather for a specific purpose. A picnic, happy hour, family dinner, holiday festival, sporting event, shopping trip, industry trade show can all be events. The Scrum Guide provides the purpose of the event.  Gather the necessary people together and let them decide how to proceed to satisfy the purpose for which they gathered.  The process may change over time and it could be different each time depending on the information being addressed during the event.  Don't try to make this formal, be agile about it. 

In the development team has a various domain including designer, business analyst, tester and developer therefore in the sprint planning how to all members can estimate product backlog item effectively?

By trusting others to represent their domain and discussing the overlap of work.  Consider that you are making a 4 course dinner and not software.  Each person in the group has some speciality knowledge such as pastry, wine, meat, sauces, etc.  The people would describe how much work goes into each specialty and then together come to a conclusion that will satisfy like purposes.  The person with meat specific knowledge would discuss with the sauce expert and together they would come up with an estimate of how long it will take to make the main course while also creating a plan on how both of the people can do their work and satisfy that estimate.  

In scrum guide had mentioned 3 titles including PO, SM, Developer

In the Scrum Guide there is no mention of titles.  The Scrum Guide defines roles. A role defines activities and responsibilities related to a purpose. Many people with different titles could aid in completing what is attributed to a role.  A title defines duties that a single individual will do. For example a Business Analyst will be able to aid in the work attributed to the Product Owner and some input to the work attributed to the Developers.  

Notwithstanding, what will you do if the development team is lack of members? We search on the internet has a lots of options to follow, for example: required members join fully, or allow forecast velocity and pick product backlog item, etc. I'm not sure which the effective way in the situation?

I understand those statements to mean that you do not have a dedicated team of developers to work on a single product.  given that how effective do you feel the team will be at continuously delivering usable increments of work that meet the Definition of Done?  Consider that you have a backend developer allocated to your team for 3 days at the beginning of the Sprint and a data developer allocated to your team for day 4 and 5.  On day 5, the data developer discovers something that will require rework of the backend code.  What happens?   This is why having a dedicated team of cross functional developers that are willing to do whatever work is needed in order to deliver is important.  Otherwise you are just doing a version of waterfall where you introduce checkpoints at specific intervals. 

The Scrum Team will craft a Sprint Goal.  The Developers will pick Product Backlog Items that will, when done, satisfy the Sprint Goal.  Note that the Scrum Guide states 

Through discussion with the Product Owner, the Developers select items from the Product Backlog to include in the current Sprint. The Scrum Team may refine these items during this process, which increases understanding and confidence.

Selecting how much can be completed within a Sprint may be challenging. However, the more the Developers know about their past performance, their upcoming capacity, and their Definition of Done, the more confident they will be in their Sprint forecasts.

Notice that there are many things that can come into consideration when they Developers select how much can be completed.  But the key to all of them is that the Developers have worked together enough to be able to anticipate how the entire group works and what they can complete. If you have a non-dedicated team where the people with specialized skills can change each Sprint, you will not be very successful.  You mentioned "forecast velocity".  That is only applicable to a consistent team.  

For an organization to be effective with Scrum and for that matter agile, the organization must be willing to change.  Introducing terms and meetings does not mean you have introduced Scrum.  

So, I'm feeling amazing when reading your comment  Daniel Wilhite -> Thanks for your support. I'm so sorry you guys because some of terms that I don't use exactly.

1. Following your comment, I understand that sprint planning is an event, and the purpose is complete 3 topics including Why is this Sprint valuable?, What can be Done this Sprint?, How will the chosen work get done?

Notwithstanding, what will you do if the development team is lack of members? We search on the internet has a lots of options to follow, for example: required members join fully, or allow forecast velocity and pick product backlog item, etc. I'm not sure which the effective way in the situation?

2. Sorry you, my question means that the team member was absence in the sprint planning event, what will you do?

The SM should wait and see if any of the developers brings this up during the sprint retrospective, and if not, they should ask an open ended question around that area (but not directly singling out the absent member) to see if that triggers a discussion, because at the end of the day its up the the developers how they wish to handle such situations (self-managing cohesive team) as the SM has no authority and should never tell the developers what to do, especially when the scrum guide explicitly states that no one can tell the developers what to do. 

2. Sorry you, my question means that the team member was absence in the sprint planning event, what will you do?

This comes back to the trusting of others.  If a developer is not available during Sprint Planning, that individual has to trust that others will represent them to the best of their ability. By the time Sprint Planning is occurring all of the items at the top of the Product Backlog should have been discussed and refined to a point that all of the Developers understand the problem.  So they should be able to create a Sprint Backlog that will not overwhelm the team based on what they know at the time. Remember that when the Sprint Backlog is created the entire development team is responsible for the work done to achieve the goal.  It isn't a time for each developer to pick the work that they will be doing during the Sprint.  The Sprint Goal is a shared commitment. The Sprint Backlog is a shared body of work.  If your team is using Sprint Planning to pick individual work items then as Scrum Master you might want to help them understand the concept of shared commitment, shared responsibility, shared efforts. 

As @Scott Anthony Keatinge mentions the absence of the team member should be discussed at the Sprint Retrospective if the team feels it is an issue.  The team should decide how to handle the situation when it occurs.