What the comparison should focus on
Most investors compare SPY and QQQ by headline returns, but a better comparison includes volatility, concentration, and how those traits affect real-world holding behavior.
This is why a calculator page should show both total return and annualized return, while also reminding users that the ride to get there can look very different.
Why start-date sensitivity matters
A start-date backtest is useful because the result changes materially based on whether an investor began before a bull market, a valuation reset, or a long sideways period.
That also makes the page more useful for search because it answers a much sharper question: what would have happened if I started on a specific date?