Tuesday, September 7, 2010

Confidence Bands for Universal Scalability Models

In the recent GDAT class, confidence intervals (CI) for performance data were discussed. Their generalization to confidence bands (CB) for scalability projections using the USL model also came up informally. I showed a prototype plot but it was an ugly hack. Later requests from GDAT attendees to apply CBs to their own data meant I had to do something about that. I tried a lot of things in R that didn't produce the expected results. Ultimately, I was led to explore the ggplot2 package—the "gg" stands for grammar of graphics. A set of ggplots, corresponding to the VAMOOS stages of USL analysis, is shown in Figure 1.