What is the Difference Between Run Chart and Control Chart?
🆚 Go to Comparative Table 🆚Run charts and control charts are both graphical tools used to monitor and analyze data over time, but they have different analytical and reporting abilities. Here are the main differences between the two:
Run Chart:
- A run chart is a simple line plotting a value over time.
- It is useful for exploring and displaying the variation and trends in your data, and for testing hypotheses or assumptions about your process.
- Run charts can help generate ideas for improvement or further investigation using techniques such as stratification, segmentation, or Pareto analysis.
- They are suitable for use when you have less data or when you do not have enough information to create a control chart.
Control Chart:
- Control charts are more sensitive than run charts and provide more detail.
- They have a 'mean' or average which is plotted on the chart.
- Control charts have upper and lower control limits, which are calculated based on the statistical properties of your data.
- They help distinguish between common and special causes of variation within a process.
- Control charts are useful for identifying special-cause variation in a process and identifying early signs of success in improvement initiatives.
- They should be used when you have more than 15 data points and want more insight into your data.
In summary, run charts are simpler and more suitable for exploring data and testing assumptions, while control charts provide more detailed analysis and help distinguish between different types of variation. Control charts are more appropriate for monitoring processes and identifying improvement opportunities.
Comparative Table: Run Chart vs Control Chart
Here is a table comparing the differences between run charts and control charts:
| Feature | Run Chart | Control Chart |
|---|---|---|
| Definition | A run chart is a graph that displays observed data in a time sequence. | A control chart is a statistical tool that graphically presents process variation over time. |
| Components | A run chart typically includes data points, a line connecting the data points, and a median (central line). It does not contain upper or lower control limits. | A control chart consists of data points, a central line (average), upper and lower control limits, and sometimes specification limits. |
| Purpose | Run charts help spot upward and downward trends and provide a general picture of a process. | Control charts determine process stability and performance, in addition to visualizing shifts or trends. |
| Versatility | Run charts can track any metric over time, such as sales, wait times, production, etc. | Control charts monitor the average or centering and the variation of the distribution of data from the process. |
| Interpretation | Run charts do not include upper or lower control limits, so they are less informative about process stability. | Control charts use control limits and sometimes specification limits, providing more information about process stability and acceptable variation. |
In summary, while both run charts and control charts are used to analyze data in order to understand process trends, control charts add statistical control limits to determine stability and performance, making them more informative about process behavior.
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