When we started our surveying business in the 90's, our quality control efforts were focused on catching transcription errors. There was certainly plenty of opportunities to make mistakes. First a surveyor would record measurements from a tape or laser onto note paper (opportunity #1). Then they would enter this information into CAD and draft the floor-plan (opportunity #2). Next, areas calculated in CAD would have to be entered into Excel (opportunity #3) to calculate common area gross-ups . Finally, the final area numbers would be typed back into the drawing (opportunity #4)
We developed a set of control activities to guard against these sources of error, including redundant measurements, check-sums as well as a rigorous review process. All these steps contributed to our ability to achieve ISO 9001 registration in 2005.
Today we have eliminated the risk of transcription error. Surveyors now use Bluetooth equipped lasers to enter measurements directly into mobile computers. (no more opportunity #1) We use special software that allows the drawings to be created on site while keeping an audit trail of all measurements (no more opportunity #2). We have developed special software that extracts area information directly out of CAD and performs all necessary gross-up calculations. (no more opportunity #3) This same software then enters the rentable numbers back into the drawing and outputs a complete Excel building report (no more opportunity #4) 
Our current method allows data to be captured electronically from the very beginning. At no point in the process are numbers typed or copied by people.
