Simplifying Software Estimation

Presented at GDG MAD in July 2020.

Transcript

1. Pratul Kalia @PRXTL • OBVIOUS.IN SIMPLIFYING SOFTWARE ESTIMATION
2. SOFTWARE ESTIMATION STEVE MCCONNELL 2006, MICROSOFT PRESS
3. WHAT IS AN ESTIMATE?
4. LET’S DRIVE FROM ONE END OF THE CITY TO ANOTHER! “How much time will it take to finish all these things?”
5. Estimates always have a probability.
6. Targets are not estimates!
7. THE TRAIN LEAVES AT 4.40 PM! “Here are a bunch of things we have to get done by X”
8. Are you chasing a target or an estimate?
9. PRESSURE & BAD ESTIMATES
10. — ALL ENGINEERS “Okay, that is a bit of work but I’m sure I can do it in 3 days.”
11. Stop putting yourself in unreasonable situations.
12. There are no prizes for getting there fast!
13. — PARKINSON’S LAW “Work will expand to fill all available time.”
14. (that is… if teams have lots of extra time, more work will magically get created.)
15. — GOLDRATT’S STUDENT SYNDROME “Given lots of time, students will delay studying until the last possible moment”
16. Underestimation is worse than Overestimation! Stastically reduced chance of on-time completion.
17. Engineers are too optimistic already.
18. OTHER SIDE EFFECTS… Poor technical foundation, worse in the long run.
19. OTHER SIDE EFFECTS… Unproductive, emotionally draining behaviours.
20. OTHER SIDE EFFECTS… - more status meetings! - frequent re-estimation! - interim releases!
21. OTHER SIDE EFFECTS… - meetings to cut scope! - fix bugs arising from hacks!
23. THE CONE OF UNCERTAINTY
25. “As the project progresses, estimates become more accurate.”
26. (yes that’s quite , isn’t it.)
28. It is easily possible to do worse… but not better.
29. The Cone does not narrow itself.
32. Stop doing first-number-in-your-head estimates! It sets the wrong expectation!
33. ⏱
34. Even a 15-minute estimate is exponentially better than an instant one.
35. INCLUDE EVERYTHING. Some requirements are stated. Others are implied.
36. INCLUDE EVERYTHING. Deployment setup Maintaining build scripts Code reviews
37. INCLUDE EVERYTHING… Writing documentation Onboarding new team members
38. INCLUDE EVERYTHING! Creating test data Upgrading dependencies
39. FACTORS THAT INFLUENCE ESTIMATES
40. Size of the software! The biggest contributor to project effort and schedule.
41. As size increases, effort goes up exponentially. Exponentially. Not linearly.
42. Programmer capability. Time constraints. Team continuity. Required reliability.
43. COCOMO-2 software estimation model.
44. IMPROVING YOUR ESTIMATES
45. I hope you use story points of some type.
46. STORY POINTS. Mark of complexity They don’t (necessarily) represent time!
47. STORY POINTS. (for e.g. A team using 1/2/3 points for a project.)
48. STORY POINTS. A junior engineer takes 5 days to finish a 3-point task.
49. STORY POINTS. A senior engineer takes 2 days to finish a 3-point task.
50. The time taken is different. But the complexity is similar!
51. NOT COMPLEX… Create a “lint step” on the CI server
52. NOT COMPLEX… Add “patient has already visited” option to Overdue list
53. COMPLEX? Allow Blood Pressure measurements to be deleted
54. The Law of Large Numbers
55. “If you create one Big Estimate, your error(s) will either be completely on the high side, or the low side”
56. “but if you create multiple Small Estimates, some will be on high side, some on the low side.”
57. “… so the errors will cancel each other out, to some extent.”
58. COMPLEX? Allow Blood Pressure measurements to be deleted
60. ALSO COMPLEX Sync Protocol Drugs across all facilities and display in the app
62. Some tricks!
63. TRICKS! Do a detailed task breakdown: spend some time!
64. TRICKS! Think of the “worst case” while estimating.
65. TRICKS! Compare different stories of similar complexity.
66. TRICKS! Use a project management tool that understands “velocity”.
67. TRICKS! Engineers should break down tasks and estimate them.
68. TRICKS! Look at past data for your team, for similar type of work.
69. TRICKS! Measure yourself privately
70. NEGOTIATIONS & AGREEMENTS
71. An estimate is a conversation, and a negotiation.
72. Engineers “own” the estimate… but Management “owns” the target.
73. The goal of estimation is NOT pinpoint accuracy!
74. People want to understand VALUE in comparison to EFFORT.
75. Do t-shirt-sizing with all stakeholders.
76. VALUE EFFORT A: S M B: M S C: S L D: XL M
77. Separate people from the problem.
78. Focus on interests, not on positions.
79. Come up with options that benefit everyone.
80. Either everyone wins, or everyone loses.
81. GO FORTH AND ESTIMATE!