It all started when my colleague and I noted that we had used the same data to calculate Cpk, but ended up with different results. This led us down an Alice in Wonderland-like path of Google searching, Wikipedia reading, and blogosphere scanning. After several days of investigation, we determined that there was no consensus on how to properly calculate estimated standard deviation. Knowing that there must be a misunderstanding and that this should be purely an effort based on science, we decided to get to the bottom of this.
Did first-class passengers on the Titanic get preferential treatment during the evacuation? James Cameron’s movie certainly seems to suggest so, but let’s look at the data.
Pick’s Theorem is a simple way to calculate area. This theorem is particularly useful when calculating the reduction of square feet (or square meters) that was achieved by improving a process layout. To use Pick’s Theorem, overlay a sketch of the area that you want to calculate onto a square grid of points. The grid of points should be fine enough that any bend on the boundary coincides with a grid point.
Looking for something to do? Why not run a continuous variable gage repeatability and reproducibility test? Our experience is that while many organizations have their key measurement devices on a calibration schedule, calibration simply isn’t enough. Gage R&R tests provide insights into how the users interact with measuring equipment and can uncover issues such as: bias, linearity issues, accuracy issues, and of course, repeatability and reproducibility issues.