A run chart is a type of chart that displays the measurement of a series over time. Run charts are often used to monitor the performance of a process, with the focus on process improvement.
Run charts can be used for any process or activity where you need to track how well it's performing and the trend. For example, you may use a run chart to determine the shift in the process over time or to check if the quality of your products is improving or deteriorating.
What Is a Run Chart?
You "might not" find the run chart in the seven basic quality tools list. However, it replaces Stratification at some places and is shown in the list of seven basic quality tools.
A run chart is similar to a Point Chart, where a line connects points. You have the time (or date) on which data was collected on the X-axis. Y-axis shows the value of data. In the case of the point chart, each point represents one sample.
Run charts are also similar to Control Charts used in Statistical Process Control (SPC), but it does not have control limits (UCL and LCL).
In the modern data science context, you can consider this similar to the Time Series.
What is a Run Chart Used for?
Run charts help detect patterns and trends in data. They're also helpful when multiple variables are being measured. You can see the relationship between two variables by plotting them against each other.
In general, they are good tools for:
• Finding the trend in the data
• Identifying seasonal variations
• Monitoring changes in behaviour over time
• Detecting outliers
What Are the Five Good Features of a Run Chart?
The following five features make a Run Chart an excellent visualization tool.
1. Easy to Understand and Interpret
You can understand a run chart in just seconds. It's straightforward to read and interpret.
2. Can Be Easily Customized
You can customize the appearance of a run chart using different colours, fonts, etc.
3. Great for Visualizing Trends
It's easy to spot trends in the data with a run chart. The lines connecting the points show how the values change over time.
4. Efficient to Create
It's very easy to create a run chart using Excel.
5. Flexible to Use
You can use a run chart for almost every kind of data analysis. You can even use it for non-time series data.
Tools for Creating a Run Chart
Various tools can be used to create a Run Chart.
1. Manual: Using a pen and paper: This method can work only if the data is small.
2. Microsoft Excel: This is the most common tool used to create a run chart.
3. Minitab: Minitab is advanced statistical software Six Sigma professionals use. You can draw a Run Chart using Minitab. To take the run chart to the next level, you can do a Time Series analysis on it. See below an example of Time Series analysis done to predict the future values.
4. Python: Python is a programming language that can be used for many different purposes. It is one of the most popular languages used today for data analysis. You can draw publication quality and professionally looking Run Chart using Python, or even conduct the Time Series analysis.
5. R Programming: R is a programming language used for complex statistical analysis. Like Python, you can use R Programming to draw a publication-quality Run Chart or to conduct the Time Series analysis.
Run Chart is a valuable tool in quality management. Run charts are sometimes called trend lines because they resemble a line graph.