# Question: In the absence of an explicit formula we can estimate

In the absence of an explicit formula, we can estimate the change in the option price due to a change in an input-such as σ-by computing the following for a small value of :

a. What is the logic behind this calculation? Why does need to be small?

b. Compare the results of this calculation with results obtained from BSCallVega.

a. What is the logic behind this calculation? Why does need to be small?

b. Compare the results of this calculation with results obtained from BSCallVega.

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