A Tableau control chart is a graph used to study how a process changes over time. All processes have some variability. That’s normal. But large shifts or swings are cause for study and indicate something has changed about the way your process is behaving.
A control chart contains the following basic elements:
- The time series data itself - yards thrown (y-axis) per game played (x-axis) as a simple line plot.
- The average line - the arithmetic average of yards thrown per game
- The control limits, computed in various ways from the data itself:
- UCL - the Upper Control Limit
- LCL - the Lower Control Limit
Signals:
- Outliers - data points either above the UCL or below the LCL
- Trends - 6 or more points either all ascending or all descending
- Shifts - 9 or more points either all above or all below the average line