T-shirt sizing - Estimating workload and capacity without false precision

T-shirt sizing is a great way of estimating the relative size or level of effort of a set of tasks. Effort and cost discussions are significantly easier when decoupled from hours and dollars. It lets people focus on the problem definition and possible approaches without getting hung up on absolute values.

  1. Size some work items relative to each other. "This one feels maybe twice the size of this other one". 
  2. Bin the sorted items in arbitrary groups (T-Shirt sizes) Small, Medium, Large, etc. based on the amount of work or complexity.  
  3. New items are sized the same way when they are first introduced. They are compared to the existing backlog and slotted into the buckets.
This process gives you a feel for work and relative complexity without resorting to false precision for specific days and hours. Velocity and Capacity can be extrapolated later after tasks of various sizes are completed. Start with relative sizing and then iterate closer to absolute sizing as you know more.

People struggle with sizing.  Management wants to how much it will cost or how many people and days it will take.  We want to provide a way of describing effort before we really know what a unit of work costs or hours they take. The two most common issues are
  1. The desire for precise estimates before enough is known for those estimates to be real.
  2.  Confusion on whether the size represents complexity or the amount of work. It represents both.  This is not precise.  It can't be.  Assume that complexity and scope combine in some way to create a single value that will eventually convert into hours and material. 

Plan, Do, Measure, Adjust

You'll have to work out the size ranges for Small Medium and Large and then possibly adjust them.  I tend to use Planning Poker style Fibbonici sizing for bin sizes.  In other situations,  just the notion of size being a couple times larger than the previous bucket is good enough.


Links

You can find Agile sizing techniques via any search engine.  Wikipedia has a general article on software sizing.

Revision History

Created 2024 02

Comments

Post a Comment

Popular posts from this blog

Understanding your WSL2 RAM and swap - Changing the default 50%-25%

Image
The Windows Subsystem for Linux operates as a virtual machine that can dynamically grow the amount of RAM to a maximum set at startup time.  Microsoft sets a default maximum RAM available to 50% of the physical memory and a swap-space that is 1/4 of the maximum WSL RAM.  You can scale those numbers up or down to allocate more or less RAM to the Linux instance. The first drawing shows the default WSL memory and swap space sizing. The images below show a developer machine that is running a dev environment in WSL2 and Docker Desktop.  Docker Desktop has two of its own WSL modules that need to be accounted for.  You can see that the memory would actually be oversubscribed, 3 x 50% if every VM used its maximum memory.  The actual amount of memory used is significantly smaller allowing every piece to fit. Click to Enlarge The second drawing shows the memory allocation on my 64GB laptop. WSL Linux defaults to a maximum RAM size of 5
Read more

Installing the RNDIS driver on Windows 11 to use USB Raspberry Pi as network attached

Image
I do a lot of my development and configuration via ssh into my Raspberry Pi Zero over the RNDIS connection. Some models of the Raspberry PIs can be configured with  gadget drivers  that let the Raspberry pi emulate different devices when plugged into computers via USB. My favorite gadget  is the network profile that makes a Raspberry Pi look like an RNDIS-attached network device.  All types of network services travel over an RNDIS device without knowing it is a USB hardware connection. A Raspberry Pi shows up as a Remote NDIS (RNDIS) device when you plug the Pi into a PC or Mac via a USB cable. The gadget  in the Windows Device Manager picture shows this RNDIS Gadget connectivity between a Windows machine and a Raspberry Pi. The Problem Windows 11 and Windows 10 no longer auto-installs the RNDIS driver that makes magic happen. Windows recognizes that the Raspberry Pi is some type of generic USB COM device. Manually running W indows Update  or  Update Driver  does  not  install the RNDI
Read more

DNS for Azure Point to Site (P2S) VPN - getting the internal IPs

Image
I wanted to access all my Azure resources without making any of them visible to the Internet.   The easiest give my local machine access to everything on my Azure Virtual Network (VNET) was to connect to it over VPN. It turns out creating Azure VPN gateways and connecting to Azure VPN endpoints is easy.  There are some subtleties in getting DNS name resolution to work that can confuse when first starting out. Setting the Stage There are a few ways to get to Azure endpoints and resources that are blocked from the internet.  We can  Create a Point-to-Site connection from our local machines to Azure Network Gateways Create a Site-to-Site network connection from our local networks to Azure Network Gateways. Use Bastion Hosts Use Cloud Shell Leave everything open to the internet. I chose a Point-to-Site (P2S) VPN connection that connects from my laptop to a VNet Gateway.  That joins my laptop
Read more