Question

We use statistical process control charts to get a better handle on the variation in our data. These tools make the process performance visible; determine if the improvement is significant; and determine if the improvement is maintained over time. For this assignment, we will explore a run chart. Discuss what a run chart is. What type of data can be used with this tool? What are the steps used to analyze a run chart? Identify and discuss the four run chart rules?

Answer 1

Run chart is a process improvement tool, which transforms the set of input with the help of various activities into the output.

With this tool data such as measurement levels, observations, time and factors are necesssary to form a run chart and find the pitfalls in the process.

To analyze a run chart following steps are used :

a. Collection of data either in sequential or chronological orders.

b. Plotting and dividing the data on the x and y axis.

c. Selecting a appropriate scale and drawing vertical lines on x axis and horizontal lines for nonrandom observations and calculate mean/median.

d. Observing the chart for the variations, and monitor the process for the consistency.

Chart rules :

a. Shift : It can be done for six or more points on chart below or above the median. As this rule is based on statistic probabilities avoid skip values falling on median.

b. Trend : As values do not break or make trend avoid values which are going up or down with five or more points.

c. Runs : Counting the number of times data line crossing median can determine the number of runs in the chart.

d. Astronomical point : Larger number unusal than other values is known as astronomical point in chart.