Tools for Working with Data

It is important to collect and analyze data as part of the current state during the planning phase of PDCA.

The tools for working with data, featured below, are geared to help collect reliable and relevant data as well as describe and present it in a way to detect trends and patterns.

The following are tips for consideration when using these tools:

• Decide on the type of data to collect and what kind of analysis tools to use.
• Select output metrics that quantify the overall performance of the process, such as quality, speed, lead time, cost; and process metrics that measure performance at key points in the process, such as time per task, in-process errors, exceptions.
• Create a data collection plan and ensure consistent measurement of data. A basic check sheet is one example of a data collection form.
• Use statistical and data display methods to present and analyze the data in search for trends, patterns, and potential sources of variation. Time series plots (run charts) are an example of one such technique.

The tools listed below provide an overview, tips, example, template, and a short explainer video.

Basic Check Sheet

The basic check sheet is used to collect data in real time at the location where the data is generated. It is typically used for collecting failure information or defects at specific process steps or times. A defining characteristic of a check sheet is that data is recorded by making marks (“checks”) on it.

Instructions:

• Determine the specific data to be collected.
• Determine the time period (e.g., day, week, shift, etc.) to be covered by the form.
• List the issues (failures or defects) in a column on the left side of the form and leave space to allow marks whenever someone finds that issue on the right side.
• Include time element, as appropriate, for collecting the data in the column headers on the right side (e.g., days, weeks, etc.)

Tips:

• Design a new check sheet, tailored to the specific situation, every time you collect data.
• Pilot test the form and make changes as needed.
• Train the data collectors on using the form.

Basic Check Sheet Template

Basic Check Sheet Example

Time Series Plot (Run Chart)

The purpose of the time series plot (also referred to as run chart) is to show data points in the order in which they occurred. It is a great way to visualize long sequences of data and help identify variations in the process over time. It is easy to construct, even by hand in the field, and tells a quick visual story about trends and significant changes.

Instructions:

• Collect data and make sure to track the order in which the data was generated by the process.
• Mark the data units on the vertical (y) axis and mark the time unit on the horizontal (x) axis (e.g., hours, days, weeks, etc.).
• Plot the data points on the chart and draw a line connecting them in a sequence.
• Determine the median and draw a line at that value on the chart, then analyze the trends.

Tips:

• Use time series plot (run chart) to visually depict how a process is performing as well as to track and communicate improvements.
• Use the following broad guidelines to analyze the trends in a time series plot (run chart):
  • Count the number of points not on the median.
  • Circle and count the number of “runs” (a series of consecutive points that do not cross the median). Consider whether there are too many or too few runs – this may indicate special cause variation in the process.
  • Six or more values in a succession above or below the median line is considered a shift, which indicates a change in the process.
  • Five or more consecutive points consistently increasing or decreasing generally indicates a trend.

Time Series Plot (Run Chart) Template

Time Series Plot (Run Chart) Example