Run Chart

RUN CHARTS/TIME PLOT/TREND CHART

OVERVIEW

PURPOSE

In-depth view into Run Charts--a quality improvement technique; how Run charts are used to monitor processes; how using Run charts can lead to improved process quality

USAGE

Run charts are used to analyze processes according to time or order. Run charts are useful in discovering patterns that occur over time.

HISTORY

Run charts originated from control charts, which were initially designed by Walter Shewhart. Shewhart developed a system for bringing processes into statistical control by developing ideas which would allow for a system to be controlled using control charts. Run charts evolved from the development of these control charts, but run charts focus more on time patterns while a control chart focuses more on acceptable limits of the process.

INSTRUCTIONS FOR CREATING A RUN CHART

Step 1 : Gathering Data

To begin any run chart, some type of process or operation must be available to take measurements for analysis. Measurements must be taken over a period of time. The data must be collected in a chronological or sequential form. You may start at any point and end at any point. For best results, at least 25 or more samples must be taken in order to get an accurate run chart

Step 2 : Organizing Data

Once the data has been placed in chronological or sequential form, it must be divided into two sets of values x and y. The values for x represent time and the values for y represent the measurements taken from the manufacturing process or operation.

Step 3 : Charting Data

Plot the y values versus the x values by hand or by computer, using an appropriate scale that will make the points on the graph visible. Next, draw vertical lines for the x values to separate time intervals such as weeks. Draw horizontal lines to show where trends in the process or operation occur or will occur.

Step 4 : Interpreting Data

After drawing the horizontal and vertical lines to segment data, interpret the data and draw any conclusions that will be beneficial to the process or operation. Some possible outcomes are:

Trends in the chart
Cyclical patterns in the data
Observations from each time interval are consistent

MY RUN CHART EXAMPLE

Problem Scenario: To determine how much time spend on the internet throughout the entire month

Data

Day	Hour/s	Day	Hour/s
(Week1) Mon	3	(Week3) Mon	2
Tue	4	Tue	1
Wed	3	Wed	2
Thur	4	Thur	4
Fri	5	Fri	6
Sat	2	Sat	1
Sun	5	Sun	1
(Week2) Mon	1	(Week4) Mon	1
Tue	3	Tue	1
Wed	1	Wed	2
Thur	3	Thur	5
Fri	4	Fri	7
Sat	6	Sat	3
Sun	1	Sun	4

Run Chart

Interpretation:

Friday and Weekends are usually the longest time spent in the internet while Monday and Wednesday are the shortest time spend on net. In term of the month, generally the time spent is rather irregular.

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