Question

How do you rate the critical worth of a movie star?
I am not talking about a box-office based worth. I am talking about the talent-wise worth of an actor. My starting point is a recent poll on the greatest British actors/actresses, especially the actresses, as the names represent the people I feel attracted to while I am deciding for a movie (i.e., Judi Dench, Julie Walters, Maggie Smith, Vanessa Redgrave, Julie Andrews, etc.).

So, What is the right formula to evaluate the performance of an actor in the success of a movie?And, How should we evaluate the performance of an actor even if the movie is a failure?

If you can come up with the right formula you may be able to reach those above names as the most powerful keys to success for a movie, hence they should get the highest critical marks.

The starting point of your formula in the case of a successful movie needs to be the critical value of the movie as a whole (you can use RottenTomatoes critic score, or you can interpolate between different rating-based sources, Yahoo! Movies and Imdb, for instance).

In the case of a failed movie (i.e., rotten quality), the evaluation of an actor that goes above the critical value of the movie needs to be what we require as a measure of talent. In such cases, take out the actor from the movie and give a second value to the movie, how much change to the critical value of the movie would you see without the inclusion of that actor? In other words, did the actor disappear with the movie, or become the sole critical likeable figure to watch within a band of scattered tasteless garbage, or separate himself/herself from the movie completely where you can take out the part played and be able to make a critically successful short movie? Decide for yourself...

Give your grades and find the right figure to use. I will do so for myself.