Understanding the Path
Trend charts are a crucial Six Sigma tool. Making decisions based on small samples of data can present an inaccurate representation of facts. Small data samples typically fail to present the true situation based on varied factors. The best decision making practices look at the past, present and future, in depth. Leaders make better quality decisions when they understand varied factors and true performance.
A Proven Track Record Using Trend Charts
Trend charts provide a clear indication of where you have been, where you are at and where you are going. They capture detailed and specific data, over specific time periods. These charts are not simple short bursts or snapshots of data. The value of a trend chart comes with time. The graphical representation of time series data (information in sequence over time) shows the trend line or curve that reveals a general pattern of change. A good trend chart has the following characteristics:
- Title: Accurately describes the subject of the chart.
- Labels: Clearly identifies information on the vertical Y-axis and horizontal X-axis to describe the measurement and the time period.
- Legend: Differentiates the plotted lines.
- Appropriate Scales: Narrow enough to show variation.
- Limited Characteristics: Helps avoid confusion from too many lines.
- Time Frame: Appropriate and encompassing.
- Notations: Made on any major spikes.
- Targets or Goals: Noted on the chart for reference.
- Who Prepared the Chart: In case there are questions about the chart or the data.
Analyzing performance data over time, allows for a variety of situational factors. All processes vary, so single point measurements can be misleading. Displaying data over time increases understanding of the real performance of a process, particularly with regard to an established target or goal.
Leaders make better decisions based upon factual clarity. Trend charts bring that clarity to the decision making process. History is a great teacher and we learn a great deal from these representations. Past performance over time gives us a better understanding of the facts under varied conditions. This data then allows us to project and forecast with a much higher level of accuracy as to the future performance of any given situation.