Looking at the project performance of organizations such as US’s NASA or the UK’s Department of Defence in isolation can make it hard to understand what a particular percentage cost overrun or delay in months actually means.
Below the performance of the two is compared. The portfolios are relatively similar in scope, one containing 10 projects the other 15. Cost overruns are relatively similar too 15% vs. 19% of initial budget. However, the Department of Defence experiences longer project delays.
Nonetheless, estimation appears worse at NASA since all projects are delayed and over budget, and this is not the case at the Department of Defence.