A portfolio manager's skill can be measured by the fund's:

A portfolio manager's skill is best reflected by the fund's alpha. Alpha represents the excess return that an investment generates relative to its benchmark index after adjusting for risk. It effectively measures the value that a portfolio manager adds through their investment decisions and asset allocation strategies. A positive alpha indicates that the portfolio has outperformed the benchmark, which suggests that the manager has skillfully identified opportunities that have led to superior returns.

In contrast, beta measures a fund's sensitivity to market movements, indicating the level of systematic risk in relation to the broader market. While a high beta may imply that a portfolio is more volatile and could offer higher returns in a rising market, it does not directly measure the manager's skill in generating excess returns.

Volatility refers to the degree of variation in a fund's returns over time, while standard deviation measures the amount of variation or dispersion from the average return. Both volatility and standard deviation are more concerned with risk rather than the manager's ability to outperform the market. Therefore, while these metrics provide useful information about risk characteristics, they do not capture the performance attributable to the manager’s strategy or decisions.

In summary, alpha is the most appropriate measure of a portfolio manager's skill because it directly correlates with the ability to achieve returns above