Here is another great article from our friend Adam Stoehr of the National Quality Institute. The National Quality Institute, http://www.nqi.ca, are a Canadian partner of BPIR.com. Adam’s article describes a personal use for run charts (pardon the pun) and their power in revealing trends.
Graphing Marathon Measures 2 – Run Chart Run
Adam Stoehr, MBA
Vice President, Education, National Quality Institute
Before we draw some graphs, let’s set some general ground rules for chart creation.
- Rule 1: Make sure you have a clear purpose for your graph and that it will convey an important message.
- Rule 2: Try to use simple pictures to depict complex data.
- Rule 3: Try to make your data talk and tell interesting stories.
- Rule 4: Remember to adapt your graph to suit the audience.
- Rule 5: Don’t be afraid to experiment with various options and graph styles.
In this article we’ll focus on the “run chart” which is one of the simplest and most-used charts available.
Basically, run charts have two rules.
- Rule 1: The lines should represent data over time
- Rule 2: The lines should represent data in chronological order
It’s important to point out that the data does not represent a snapshot in time like we saw with the bar chart in Figure 2 from last month’s newsletter. The best way to explain the over time (run chart) vs. snapshot in time (bar chart) is that the data in the past on a run chart will not change. For example the number of KM’s that I ran in May 2011 will never change because May 2011 is in the past.
The first pattern to look for is if there are 5 or 6 points in a row that steadily increase or decrease. In figure 3 you can see this in both directions. For example from May 2008 to Jan 2009 you can see 7 points in a row that are increasing. Luckily for me (considering what I’m measuring) between July 2010 and March 2010 there is the opposite pattern of weight loss.
The second pattern to look for is if 5 or 6 points in a row are on the same side of the average/goal. This is evident in figure 3 between November 2009 to present. If either of these patterns are present then it’s a pretty good sign that your process is changing (hopefully for you in a positive direction). So my running schedule and my weight loss have been trending in the right direction according to my goals.
With all charts it should be pretty obvious what story you are trying to tell. You should be able to make one or two statements about the data without thinking too much.
At the end of the day you want the charts to tell stories. For example looking at the four run charts we can make the following fact based statements.
- Figure 1: I have been consistently meeting or exceeding my goal of running 100 km a month since May 2010. I only missed the goal once in January 2011.
- Figure 2: Sunday is my most active day with 65 total runs and Saturday is my least active day with 33 total runs.
- Figure 3: My weight has been trending downward and has been consistently below my 3 year average weight over the last 6 months.
- Figure 4: January/February and July/August have been my most challenging times of year to keep my weight down. April/May and November/December have been my best months for weight loss.
Common uses for bar charts include:
- Any data over time
- Revenue trends
- Stock prices
- Process performance
In next month’s Quest for Excellence we’ll look at Scatter Diagrams to see relationships between data.
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