配对t检验和成组t检验相比（）
A.更不容易获"差别有显著性"之结论
B.更不容易发觉两总体均数间存在的差别
C.统计检验效率更高
D.不论在什么条件下都不能有同样的统计检验效率
E.不论在什么条件下都有同样的统计检验效率
参考答案：C
解析：若是配对设计，每对数据的差值必须服从正态分布；若是成组设计，个体之间相互独立，两组资料均取自正态分布的总体，并满足方差齐性。即凡自身对照资料可以采用配对t检验，两组均数比较采用成组t检验，后者需进行方差齐性检验，对非正态分布或方差不齐的数据进行适当的变量转换，待满足正态方差齐后，用转换的数据进行t检验；若转换数据仍不能满足正态方差齐要求，改用t'检验或秩和检验；但变异系数太大（如CV＞50％）的资料应用秩和检验。在试验前组间比较差异无显著性的前提下，可进行试验后组间比较。
My dad was a fisherman. He worked hard and stayed out until he caught enough 36 to feed the family nearly every day. When the weather was bad he would 37 me to school. An old truck was used in his fishing business. When we got to the school, he would give me a big 38 on the face and tell me to be a good 39 . It was so embarrassing for me. I was 12 years old, and my dad would still kiss me goodbye! I remember the day when I decided I was too 40 for a goodbye kiss. When we got to the school and came to a stop, he had his usual big smile. He started to lean (倾斜) toward me, but I put my hand up and 41 , “No, Dad.” It was the first time I had ever talked to him that way. He had a surprised look on his face for a long time, and his 42 started to be wet. He turned and looked out of the windshield (挡风玻璃). “You’re 43 ,” he said.“You are a big boy—a man. I won’t kiss you any more.” It wasn’t long after that when my dad went out to 44 and never came back. It was a day when most of the fishermen stayed at home except Dad. He had a big family to feed How I wish I had been a man then. If I had been a man, I would 45 have told my dad I was too old for a goodbye kiss.
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