Trend & Regression Analysis Chart

The Trend & Regression Analysis Chart displays data trends over time, allowing you to analyze process performance against established limits. Using the Least Squares method, which minimizes the sum of the deviations from the fitted regression line, you can calculate the "Best Fit Line."

With this value, you can calculate the goodness of fit and the strength of the relationship. The stronger the relationship, the better the fitted regression line is at estimating the measured parameter.

The following is a list of parameters that can be charted using Trend & Regression Analysis:

• Means. Mean is the arithmetic average of a given data set.
• Standard Deviation (SD). Measure of variation representing the average deviation of values from their mean, often called sigma because the Greek letter sigma (s) is used as a symbol for standard deviation.
• Pp. Ratio of the process variability (Six Sigma) with the width of the specification limits (total tolerance), using the process standard deviation and the specification limits in its calculation and calculating sigma using the root mean square method (RMS).
• Pr. Inverse of Pp.
• Percent Defectives. Percent of the number of defective pieces.
• Ppk. Measure of actual expected fallout from the tolerance limit closest to the process mean. Ppk is equal to the smaller of Ppu or Ppl.
• Ppu. Difference between the upper specification limit and the process mean, divided by three standard deviations. The standard deviation is calculated using the root mean square (RMS) method. Also known as Ppk (upper).
• Ppl. Difference between the lower specification limit and the process mean, divided by three standard deviations. The standard deviation is calculated using the root mean square (RMS) method. Also known as Ppk (lower).
• Percent Defects. Percent of the number of imperfections on a part.
• Tests (Run Chart). Examination, observation, or evaluation being performed. Also known as characteristic or feature. For example, Product Net Weight, Percentage of Salt, Volume, Inside Diameter A, Viscosity, Height, Temperature, Oxide Thickness, Torque, and Critical Defect Type.
• Subgroups (Run Chart). Measurements taken at the same period of time from a particular process. Multiple subgroups are used to analyze the performance of a process. A comment can be assigned to a specific test value or the entire subgroup. All test values will all contain the same Subgroup ID. Also known as a sampling.