问题
问答题
请简述影响预后研究质量的因素。
答案
参考答案：
一.集中性偏倚（又称就诊偏倚），控制措施有：随机化，限制，配对，分层，多因素分析。二、迁移性偏倚（又称撤离偏倚）。病人退出研究或移动到别的队列，都与预后有关。三，测量性偏倚，如果概念模糊，没有明确的判断标准，就容易出错，影响研究结果。
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请简述影响预后研究质量的因素。
参考答案：
一.集中性偏倚（又称就诊偏倚），控制措施有：随机化，限制，配对，分层，多因素分析。二、迁移性偏倚（又称撤离偏倚）。病人退出研究或移动到别的队列，都与预后有关。三，测量性偏倚，如果概念模糊，没有明确的判断标准，就容易出错，影响研究结果。
根据短文内容，从短文后的选项中选出适当的选项补全短文。 The earth is about 4,600 million years old. We humans have lived on the earth for only 35,000 years, but during this period we have changed our planet a lot in many ways. 1 All over the world, people have cut down millions of trees, so more and more kinds of animals and plants are disappearing. In big cities, cars and buses have polluted the air. Factories have also polluted the land and the water. 2 It is important to the earth. But now air pollution is destroying it and that has made a very big hole in the ozone layer (臭氧层). 3 This is very dangerous because it can cause cancer. Carbon dioxide (CO2) in the air has increased a lot. 4 it has formed a "blanket" (毛毯) around the each. 5 This makes our earth become warmer and warmer. Therefore, this causes the level of the ocean to rise. All these problems are very serious. We must do something to stop our earth from being polluted anymore.
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