## Why BE testing use 90 CI [General Sta­tis­tics]

Dear Akash,

» This is where the 90% CI comes into the equation. There is a (not more than) 5% risk associated with it (1-2*alpha).

My understanding of the reason why: the true T/R ratio cannot be at the same time lower than 0.8 and higher than 1.25. So even if you test the lower limit with a 5 % risk, and the higher limit with a 5 % risk, the overall risk still remains 5 % for the patients, not 10 %.

Regards
Ohlbe