clm.org-latency-bufferbloat.queue-time-dominatesIn instrumented software-development settings, calendar lead time is dominated by coordination and waiting rather than by touch time: distributed work items took about 2.5x as long as colocated ones — with the paper's own modeling attributing the delay primarily to the larger number of people distributed changes involve (the distributed indicator itself is not significant once people-count and other factors are controlled), alongside survey-reported cross-site delays averaging ~2.4 days versus ~0.9 same-site — and WIP correlates directly with lead time in multi-year kanban field data.
- supportsprimary-checkedAbstract
“One key finding is that distributed work items appear to take about two and one-half times as long to complete as similar items where all the work is colocated.”
calendar time, distributed vs colocated work items: ~2.5x longer (n = modification requests from two Lucent departments)
Herbsleb, J., Mockus, A. (2003). An Empirical Study of Speed and Communication in Globally Distributed Software Development. IEEE Transactions on Software Engineering, 29(6). link
- supportsprimary-checkedAbstract; elaborated in §3.3 Replication ("It appears that splitting work across sites slows the work down primarily because it requires the involvement of more people than comparable work accomplished all at one site.")
“The data strongly suggest a mechanism for the delay, i.e., that distributed work items involve more people than comparable same-site work items, and the number of people involved is strongly related to the calendar time to complete a work item.”
Herbsleb, J., Mockus, A. (2003). An Empirical Study of Speed and Communication in Globally Distributed Software Development. IEEE Transactions on Software Engineering, 29(6). link
- contextualizesprimary-checked§3.2 Modeling MR Interval (Table 2 regression discussion); replicated for Department B
“Surprisingly, given all other factors, distributed MRs do not have significantly longer intervals than single-site MRs.”
Herbsleb, J., Mockus, A. (2003). An Empirical Study of Speed and Communication in Globally Distributed Software Development. IEEE Transactions on Software Engineering, 29(6). link
- supportsprimary-checked§3.1 (delay survey)
“Averaged over all 92 respondents, the mean number of local delays was 2.1 delays per month and the mean duration was .9 days. For cross-site delays, the mean number was 1.9 delays per month and the mean duration was 2.4 days.”
mean reported work-issue delay duration, cross-site vs local: ~2.4 days vs ~0.9 days (duration difference significant, p < 0.02; count difference n.s.) (n = 92 survey respondents)
Herbsleb, J., Mockus, A. (2003). An Empirical Study of Speed and Communication in Globally Distributed Software Development. IEEE Transactions on Software Engineering, 29(6). link
- supportsprimary-checkedAbstract (via SINTEF publication record)
“WIP correlates with lead time; that is, lower WIP indicates shorter lead times, which is consistent with claims in the literature.”
WIP ↔ lead time correlation: direct correlation (n = 8,000+ work items, 5 teams, 4 years, one company)
Sjøberg, D. (2018). An empirical study of WIP in kanban teams. ESEM '18 (12th ACM/IEEE International Symposium on Empirical Software Engineering and Measurement), Oulu, Finland. doi:10.1145/3239235.3239238
- contextualizesreport-derivedSeed report, §Core idea
“Reinertsen's Principles of Product Development Flow built an entire operating doctrine on this point, observing that product-development queues are invisible inventory and that, per his practitioner surveys, only about 2% of product developers measure queues and only 15% know their cost of delay.”
Reinertsen, D. (2009). The Principles of Product Development Flow: Second Generation Lean Product Development. Celeritas Publishing. not peer-reviewed
Counter-evidence not yet searched.