Transcript for:
Estimation en Heures ou en Points de Récit dans Agile et Scrum

i get this question a lot should i estimate in  hours or story points is it allowed to estimate   in hours and mandates when using agile and scrum  what are the pros and cons of each method well by   the end of this video you'll have the answers to  all these questions and you know exactly how the   best method to estimate your future user stories  let's start with the basics why do we estimate   in the first place well the key reason behind  hours story points is that we want to estimate   work to know exactly how much work we can  accomplish in a given time for most people   and companies hours as being the preferred method  of estimation for decades because time can easily   be measured we can easily quantify time and time  is accurate but for non-mechanical activities like   software development where the outcome depends on  many intangible factors skills environment mood   energy general energy of a person information  available motivation so many things affecting the   performance of a person or a team estimations are  hard to do and often off which begs the question   if estimations are hard to do and off why are  we estimating in the first place and if you're   using agile scrum you have a product backlog a  product backlog which contains all the items that   you want to build for the customer and the product  backlog is sorted in terms of priority for most   important things valuable things for the customer  on top so why not just pick each item let's start   with the first one you pick the highest priority  item the top item stop development once you're   done you move on to the next you move on to the  next until the whole complete product backlog   completely done in production to customers why not  do that well in theory this would work this would   work really well but in practice stakeholders  upper management even your product owner will   insist that they want to see estimations they want  to know they want to have a timeline they want to   be the roadmap they want to have release dates  milestones and for all these things they need   estimations from the team and because of this  estimations are important essential in the   project if used correctly and by correctly i mean  by the correct definition of an estimation is used   an estimation is not a deadline not a target  date it's a possibility it's simply a guess   an estimation is a guess given all the  information that we have right now we are   guessing estimating that we would complete  this given amount of work in this amount of   time we are guessing how big an item is or how  long an item would take to accomplish based on   all the information that we currently have but i'm  sure that you experience that a lot stakeholders   upper management don't understand what estimations  or they think that an estimation is a correct   figure we can use the estimation to set a target  date a release date which can't be changed   so if you're experiencing this in your company  with your team explain to management that is   simply a guess you can use the google definition  of an estimation it says but it's a guess   we are guessing predicting based on the  information that we have and explain that to   your team also and the cool part with estimation  is the more we work together as a team the more   we know the product the more we know how to work  together the better we are at estimating it we   use estimations to build a road map set target  dates milestones do budgeting set goals and have   target days to communicate to customers and if  estimations are all about possibilities guesses   how easy is it to have a team of people from  different backgrounds different skills experience   how is it to have a common understanding to build  an estimation with all these profiles in a given   team it's not easy it's not easy at all and that's  especially true if you're using hours i highly   recommend that if you're using hours to estimate a  given piece of work use a range from 5 to 10 hours   if you have people in your team with different  backgrounds skill level experience an estimation   is a guess remember that is a possibility and  people generally believe and we understand that   but as soon as you give a figure in terms of hours  five hours to complete a piece of work it builds   sort of an expectation around these five hours and  if a person doesn't complete that in five hours   the trust is broken especially from stakeholders  and upper management even though they understood   but it's a guess if you give an hour  to that estimation we sort of believe   that you would complete that in five hours it  doesn't make any sense but it's like that in   the real world and if you feel that all these  issues are important to you you want to avoid   all these issues in agile scrum we usually  estimate in storyboards or t-shirt size basically   the same thing when we are estimating in hours we  ask for question how long will it take to complete   a piece of work and when estimating story points  or t-shirt size we ask for question how big is it   looks similar but reframing the question from  time to measure of how big or how small is it   game change if you want more details on how  to estimate in story points t-shirt size you   can watch this video right here i did a full  breakdown which you can use a step-by-step   guide which you can use to estimate all your  future user stories i personally like estimating   in story points and there's three main reasons  key reasons for that first there's no link between   experience skills when estimating let me give you  an example simple example let's say i'm estimating   in hours i'm gonna there's a piece of work i  say that it's five hours for me to complete it   some people might believe that other people can  complete the same task in five hours but i have   five years experience and the other person who  will be working on that might have a few months   of experience maybe the other person will take 10  hours and if while a person takes 10 hours upper   management will be not be okay with that because  i said it's going to take five hours we don't know   that multiple people estimated work and we can  deal with that when using story points storypoints  eliminate this problem because it's a universal  measure of estimating across the team everyone   from different backgrounds different skill level  experience needs to answer the question how   big is it how complex is this task to do and we  talk about this and we discuss and they agree on   a figure if you're using story points like five  if you're using t-shirt size it can be medium   everyone has agreed it doesn't matter if the  person estimating the work will do the work later   because it doesn't matter the person estimating my  work is the team not a single person and because   we used a medium large extra small five eight if  you're using story point it doesn't mean anything   it's a guess at prediction it's simply based  on the complexity and the size of something   no one if you give that figure to management  they can't tell you okay you need to meet   that figure doesn't make any sense for them  what's eight what's medium if you give hours   it makes sense for them they can see the hours  and they will make you abide to what you said   this eliminates the problem when using story  points estimating in story points is also a   relative approach when estimating in hours we take  a story this one is five hours next story this one   is eight hours but when estimating story points  let's say we have a story in sprint one which   is a story and we said that the story would be  three points in the next sprint if there's a story   which is quite similar we already know that this  story is three points because it's similar to the   previous story what we completed three points  we already know how much work is how big and   complex is three points and if we have another  story which is maybe we say that it's bigger we   know that it's not a three it's bigger than it's  three maybe it's an eight maybe it's a twenty   maybe it's a ten we don't know but it's bigger  everything is compared to each other instead of   individually estimating stuff it's easier we see  a story we see that it's bigger we compare that   to something that we know we've completed which is  smaller and we give a t-shirt size or story point   it's really really simple to estimate this way  compared to hours estimating in story points   can also be used to peel the road map to set  target days management upper management vervet   we love this prediction these releases these  target dates and we can easily do that using   story points we have a concept called velocity for  the pace of a team how many points are completed   each and every sprint by the team we can have  average velocity for three previous sprints let's   save over three previous sprints simple example we  completed the team worked on 10 story points per   sprint the average for the three previous sprints  30 divided by 3 it's 10 story points simple   example we already know that there's 20 story  points remaining until the next release 20 divided   by 10 that's our base we know that it's gonna take  two sprints to complete all the things required   for the next release remember it's a guess it's  still a prediction but we can use these story   points to predict things releases target days  coming communicate days to customers and all that   it's still possible same as for hours if you want  more tips insights on agile scrum personal growth click on the video that stands out for most on the  screen right now and i'll see you in a few seconds