Three important concepts
What is a spider diagram?
A spider diagram is a presentation of all the increments for all the inputs selected on the x-axis and presents the resulting output in the form of line graphs (Bodmer). For the most experienced in the life cycle, the total cost of ownership was used to calculate such costs. Data is organized reasonably with the help of this plot, and It displays information about many variables.
The main economic story
Allocation of scarce resources is the basis of economics. The article suggests that concerning cost-effectiveness, a bus with relatively lower present worth of the total cost of ownership is preferable for use in an area where a charged electric bus is available as back up. For instance, a coach with one extra battery and two standard chargers is most suited compared to one with one spare battery and two fast chargers as the standard chargers are inexpensive and allow for longer battery life.
The spider plot does not provide room for comparing the input variables with the output. The most influencing input variables in the scheme should cover the most considerable vertical distance as outlined in the plot. The carbon tax input does not give any significant influence on the total cost of ownership hence can as well be removed from the scheme.
The minimum and maximum deviations from the baseline are given as follows
%deviation from baseline = (value/baseline-1)*100. For instance
Baseline hospital care
Minimum; (4.8/23-1)*100= -79.13%
|Cost Savings From
(Millions of $ CAD)
|Scenario||Deviation from baseline|
|Worst Case||Baseline||Best Case||minimum||maximum|
Bodmer, Edward. “Generating Tornado Diagrams, Spider Charts, and Waterfall Graphs.” Wiley Online Library (2014).
Eschenbach, Ted G. “Spider Plots Versus Tornado Diagrams for Sensitivity Analysis.” Decision and Risk Analysis (1992): 40-46.