●●● ●●●● ●●●●● ●●●● ●●0●● ●●●0 State of nature Decision Ho is real Ho is false Don't reject Correct decision type I error 5 10 Correct decision Reject Ho type I error (a) Test power(1-B) 21/1/292021/1/29 20 Decision State of nature H0 is real H0 is false Don’t reject H0 Correct decision 1 - α type Ⅱ error (β) Reject H0 type Ⅰ error (α) Correct decision Test power (1-β)