Practical Software Measurement

Historical Data Isn’t Playing "Hard to Get"

Historical Data Collection

“No, we don’t have any historical project data collected” is the statement I hear with some frequency when speaking to organizations about their IT project estimating processes.  Ideally we use client history to calibrate and tune the project estimates we provide.  In my quest to spread the word about parametric estimating I often encounter this notion that organizations don’t believe they have historical data in a retrievable form.  In almost every case that I have been involved, it turned out that the historical data was present, just not in the form of a 1,000 rowed spreadsheet.  Often times the data is more available than the client is aware.

Our approach works at a macro level so we are seeking overall project metrics of cost, schedule, size, staffing and defects.  If the actual formal documentation of history is not available for these five core metrics, then it usually is available by leveraging various sources within the organization.  We have found it’s common to resurrect a project’s outcome by seeking feedback from the team that worked the project, however if that’s not possible due to attrition, re-org or other disrupting factors, we can usually find the project metrics through other means.  Those other means may be time and defect tracking tools, requirements analysis tools and accounting systems.  The data is almost always documented somewhere.   

It’s understandable that many organizations think of historical data as being housed and cataloged in a massive spreadsheet, and even if they do believe they have the data in that form, they doubt they would have access to that data without Herculean efforts.  Our success in retrieving what was thought to be unattainable data is accomplished by collecting these five metrics:   

Schedule – number of calendar months of duration which can be gleaned from time tracking tools

Cost – overall spend, this would be one number that we can usually get from accounting systems and time tracking tools

Staffing – again, the time tracking tools will have captured the number of staff

Size – probably the metric most misunderstood.  The most likely outcome of a size estimate is scope based so we would be seeking some “countable” entities in the form of Stories, Function Points, Business Requirements, Technical Requirements to name a few.

Defects – should there be a defect tracking tool in use, we have found it’s likely we can get the total number of defects, and commonly their severities as well

I don’t mean to over simplify the notion of historical data collection, but we have found it’s not as onerous as one may think, especially when considering the incredible value it brings to creating a sound project estimate! 

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