Figure 2.10

Are we focusing on the highest priority actions?

Focus on the critical areas

There are a few universal rules about which chart type best portrays any given set of data, and in many cases the same data set can be shown many different ways. The hard part is determining which chart type emphasizes the point you are trying to make or puts the right "spin" on the data. The following provides some general comments on different chart types.

Vertical bar chart: Vertical bar charts are used to show how values change over time. They are typically used for a limited time series (i.e., just a few years, quarters, months, or whatever time period you are working with). Vertical bar charts are good for handling multiple series for comparison purposes.

Stacked vertical bar chart: Stacked vertical bar charts convey the same information as ordinary vertical bar charts, but allow you to display subelements which contribute to the overall bar. This may be helpful in understanding changes from one period to another.

Vertical line chart: Vertical line charts are best for showing changes in a group of values over longer periods of time. They are also recommended if you are displaying several groups of data simultaneously. Control limits are often included in vertical line charts to evaluate variability.

Horizontal bar chart: Horizontal bar charts are best for simple comparisons of different individual values at one time. A vertical bar, line, area or 3-D riser chart would be more beneficial if you want to evaluate change over time.

Pie chart: Pie charts are often the best way to portray the contribution of parts to a whole. They are used to show a "snap-shot" at a specific time.

Scatter chart: Scatter charts show the correlation of two sets of numbers by plotting where the variables intersect. Scatter charts are useful when the coordinates on the horizontal scale, often time intervals, are irregular.

Histogram: Histograms show the frequency of the values in a set of data. Data is plotted in increasing or decreasing order based on the frequency count for each data value.