IHI QI 104: Interpreting Data: Run Charts, Control Charts, And Other Measurement Tools*

10 September 2022
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question
Use the following scenario to answer questions 1-2: During a clinical rotation on the medical-surgical floor of a hospital, you notice several patients have developed urinary tract infections (UTIs) associated with their Foley catheters (tubes inserted into the bladder to drain urine). Your staff physician agrees that this is a problem and offers to help with an improvement project. Together, you work through several PDSA cycles to reduce the rate of UTIs on your floor. Which of the following methods would you recommend to display your improvement data?
answer
Draw a run chart. Run charts are an effective way to view changes over time. They are much easier to interpret visually than a list of numbers or a static display of data such as a bar chart.
question
When designing the run chart, it is important to include:
answer
Units of time on the X axis The run chart should display units of time ā€” whether it's days, weeks, or months ā€” on the X axis. The Y axis is where you plot the key variable you are measuring, which in this case is the rate of UTIs.
question
What is the minimum number of data points you should usually have to look for signs of improvement on a run chart?
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10 A run chart becomes more powerful as you add more data points because there will be more opportunities to identify patterns. If you're looking for signs of improvement, usually you need at least 10 data points.
question
Which of the following is a problem with static data?
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It doesn't adequately portray variation. Summary statistics that are static in nature don't give you the appropriate picture of the variation that lives in your data. Although you can accurately display data such as the mean, median, or mode, it is not a good way to observe change over time.
question
When you are graphing a proportion or a percent, what should you look at to help you understand the bigger picture?
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The denominator of the measured value By tracking the denominator of the measured value, you can confirm that your improvement effort is really showing signs of success, and there are not other factors at work.
question
Within the following data set, what is the median? [2.5, 7.2, 2.5, 2.9, 4.7, 3.6, 4.7]
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3.6 You calculate the median by finding the midpoint of a set of numbers. In this case, the median is 3.6, because there are three values before and three values after 3.6, making it the midpoint.
question
What aspect of the run chart helps you compare data before and after a PDSA cycle?
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B and C What aspect of the run chart helps you compare data before and after a PDSA cycle?
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Which of the following is a rule for determining non-random patterns?
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A and B The best answer is A and B. A run of six points or more and an astronomical point both indicate non-random patterns. A trend of three points or fewer does not. In order to indicate a non-random pattern, a trend must consist of five data points or more.
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In the above chart, how many useful observations are there?
answer
36 Counting all the points not on the median yields 36 useful observations.
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When did a PDSA cycle occur?
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March 05 The label on the chart shows a PDSA cycle occurred in March 2005
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How many runs are there?
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12 By counting the number of continuous points above or below the median, we get 12 runs.
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Here's a table to help you apply Rule 3 to the chart:
answer
Yes, there are too few runs. There are 36 useful observations. For that number of observations, the table states that 13 or fewer runs show non-random patterns. We have 12 runs. Therefore, we can deduce that there is a non-random pattern in this chart.
question
Which of the following traits do histograms, Pareto charts, and scatter plots have in common?
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They are all visual tools to display data. Answer: B. They are all visual displays of data. Histograms and Pareto charts are types of bar charts, but a scatter plot is not.
question
What famous Italian economist is credited with the theory behind the 80/20 rule?
answer
Vilfredo Pareto The correct answer is Vilfredo Pareto. Pareto observed that 80 percent of the wealth of Italy was owned by 20 percent of the people. The Pareto chart was named after him by Joseph M. Juran.
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Which of the following BEST describes the purpose of a histogram?
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They are all visual tools to display data. Answer: B. They are all visual displays of data. Histograms and Pareto charts are types of bar charts, but a scatter plot is not.
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When drawing a histogram, which is a good number of categories to include on your X axis?
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6-12 Six to 12 categories of equal width is usually a good number to help you understand the distribution of data.
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Which of the following charts would be best to justify focusing on a few large problems and ignoring many smaller ones?
answer
Pareto chart By separating the vital few from the trivial many, a Pareto diagram helps a team concentrate its efforts on the factors that have the greatest impact. It also helps a team communicate the rationale for focusing on certain areas.