While tornado and spider charts are useful, they have some limitations:
Since the tool tests each variable independently of the others, the tool does not consider correlations defined between the variables.
The results shown in the tornado and spider charts depend significantly on the particular base case used for the variables. To confirm the accuracy of the results, run the tool multiple times with different base cases.
This characteristic makes the one-at-a-time perturbation method less robust than the correlation-based method built into Crystal Ball's sensitivity chart. Hence, the sensitivity chart is preferable, since it computes sensitivity by sampling the variables all together while a simulation is running.