Attribution Analysis of Equity Portfolio Performance

XYZ Asset Management is evaluating the performance of a diversified equity portfolio for the past year. The portfolio generated a return of 15%, while the benchmark index returned 10% during the same period. The portfolio consists of large-cap, mid-cap, and small-cap stocks, along with a small allocation to international equities.

As a portfolio manager, you are tasked with conducting an attribution analysis to understand the sources of the portfolio's excess return over the benchmark. Provide a detailed analysis that includes the calculation of allocation effect, selection effect, and interaction effect within the context of this portfolio. Discuss how each effect contributed to the overall performance and suggest areas for potential improvement in future portfolio management strategies.