On quite a few articles I see people use price of BIL ETF when compare return of SPY vs bond, for example
In below lecture, it compare AMZN vs BIL on price when calculating Sharpe ratio
https://www.quantopian.com/lectures/instability-of-estimates
This article does not seem to use yield either
https://www.quantopian.com/posts/dual-momentum-investing-strategy-according-to-dr-gary-antonacci
However as I understand, the price of bond ETF does not reflect the true return of bond, as bond ETF also has around 3% yield.
So I am wondering if I miss anything or these articles are not actual useful algos ?