We use the log-likelihood because the natural logarithm is a strictly increasing (monotonic) function, so maximizing the log-likelihood yields the exact same parameter value as maximizing the original likelihood. Additionally, the logarithm converts the product of independent probabilities into a sum, which makes differentiation much easier.
Conditions: The likelihood function is strictly positive.; The base of the logarithm is greater than 1 (e.g., the natural logarithm).
We use the log-likelihood because the natural logarithm is a strictly increasing (monotonic) function, so maximizing the log-likelihood yields the exact same parameter value as maximizing the original likelihood. Additionally, the logarithm converts the product of independent probabilities into a sum, which makes differentiation much easier.
Conditions: The likelihood function is strictly positive.; The base of the logarithm is greater than 1 (e.g., the natural logarithm).