De Mast and Trip (2007) list the following three steps in performing Exploratory Data Analysis.
- Display the Data
- Identify salient features
- Interpret salient features
The resin output variation example, 3/25/2008 posting illustrates these steps. The Ricoh team constructed a histogram of the output quantity (Display the data), noticed the bimodal nature of the output quantity (Identify salient features), and this bimodal distribution suggested that the output distributions from lines A and B were different (Interpret salient features). Histograms of line A and line B output confirmed this conclusion. Another salient feature of the histograms was the excessive variation in output quantity. This feature motivated establishment of lower and upper limits and a target value.
References
- De Mast, Jeroen and Albert Trip (2007). “Exploratory Data Analysis in Quality-Improvement Projects”, Journal of Quality Technology, 39(4): 301-311.