(n) a test procedure in which the identity of those receiving the intervention is concealed from both the administrators and the subjects until after the test is completed; designed to reduce or eliminate bias in the results
[空城计 / 空城計, kōng chéng jìㄎㄨㄥ ㄔㄥˊ ㄐㄧˋ] empty city strategy (成语 saw), cf Zhuge Liang 諸葛亮|诸葛亮 playing the guqin 古琴 zither over the open gate to his empty fort, fooling Sima Yi 司馬懿|司马懿 into suspecting an ambush; a bold front hides a weak defense; double bluff, See Also: 成语, 諸葛亮, 诸葛亮, 古琴, 司馬懿, 司马懿#64043