Here are the results as of 3 pm today for our productivity poll. I was surprised to see that "Time slicing and multi-tasking" was far and away the most popular response!

When I framed the poll question, I was thinking of time slicing by policy (i.e., where management asks a single person to divide his time/attention between multiple projects). Viewed from a cost perspective, such assignments make perfect cents [pun fully intended] - especially for small or poorly capitalized projects. But from a productivity perspective, the constant distractions inherent in this kind of multi-tasking can result in less than optimal performance. 

Carol Dekkers made me think of another possible explanation for the declining productivity we've seen over the last 15 years: the distraction of 24/7 online communication. 

Since joining the world of social media I realize my “connectivity” has grown exponentially, but not all in a good way. Even with my SPAM filters set to high, I get so much email that it is overwhelming!

 I feel like I must have ADD (attention deficit disorder) because my day is interruption after interruption (sorry TweetDeck!) and I need help (and I know I am not the only one!)

On our Software Productivity Declines Over Time post, ISBSG's Peter Hill left an interesting comment:

... your findings that 'average productivity increases with project size' might raise a few eyebrows, but the ISBSG data produces the same finding. Of course we only have data on projects that were completed. I wonder about the incidence of abandonment of large projects.

The QSM database shows a positive correlation between system size and productivity. The following chart shows PI vs. System Size regression fits for 9 different application domains (Business, System Software, Process Control, Telecom, Scientific, Command & Control, Avionics, Microcode, and Real Time). Regardless of domain, average productivity increases with system size:

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In the SLIM-Estimate user's guide, we speculate about possible explanations for the relationship between productivity and system size:

Small systems tend to have lower average PIs than large systems. We can only speculate as to the reasons, but two important influences may be management influence (the way large and small systems are planned, managed, and funded) and economies of scale.