How do you measure an alts performance?

[nport1063]

How do you measure the performance of a Alt on a chart?  Do you compare the alt to btc...or do you compare the alt to Fiat?

I understand that at the end of the day, if you want to sell your coins the alt compared to fiat is the only way to value it.  But when it comes to day to day fluctuations in price wouldn't you want to use the alt/btc chart?

Thanks