问题 判断题

在多元回归模型中,进入模型的解释变量越多,模型会越好。()

答案

参考答案:

解析:假如加入模型的额外解释变量对解释分数差异具有显著的额外贡献,那么它将会显著地提高决定系数。可见不能简单地说“进入模型的解释变量越多,模型会越好”。

阅读理解

From the beginning rivers have played an important in the life of man.Man of the earliest times used the rivers as a means of travel.Today rivers still serve as a great waterway for the transport and people.

In ancient times, man settled near rivers or on river banks and built up large empires.

Water is nature’s most valuable gift to man.Man needs water to irrigate his crops, to cook and to wash.In nations all over the world, rivers mean life and wealth.They feed and clothe the nations around them.

Water is also a source of energy and power.Man build huge dams across the rivers to control the water for irrigation and get the energy needed to drive generators.The electrical power is then directed to homes, cities, factories and television stations.

Man uses water each day.In a small way rivers help to keep man in good health and provide for his amusements.Various forms of water sports keep man strong and healthy.

小题1:Rivers have been important to man _______.

A.since they came into being

B.since the last century

C.since a few hundred years ago.

D.since the beginning of BC小题2:Man in old times traveled from one continent to another ______.

A.by air

B.by sea

C.by train

D.by bus小题3:Generators are machines that are used ______.

A.to direct electrical power

B.to control the water

C.to produce electricit

D.to build dams y小题4:Which of the following statements is true?

A.People get energy by building bridges across rivers.

B.In ancient times large empires grew up near dams.

C.People can be provided with amusements in small rivers.

D.Large rivers are still useful for transportation in modern times.

单项选择题