| 查看: 5580 | 回复: 18 | ||
| 当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖 | ||
[求助]
什么是negative control 什么是positive control？
|
||
| 什么是negative control 什么是positive control？ |
回复此楼» 猜你喜欢
申博/考博
已经有8人回复
-
291求调剂
已经有12人回复
-
一志愿A区211，22408 321求调剂
已经有8人回复
-
295分求调剂
已经有6人回复
-
一志愿中科大材料与化工，353分还有调剂学校吗
已经有13人回复
-
085600材料与化工调剂
已经有6人回复
-
期刊推荐
已经有5人回复
-
有没有接收比较快的sci期刊呀，最好在一个月之内的，研三孩子求毕业
已经有7人回复
-
又一批高校组建人工智能学院 师资行吗 不是骗人吗
已经有4人回复
-
337求调剂
已经有3人回复
» 本主题相关价值贴推荐，对您同样有帮助:
- 转载的我认为当时最考研英语作文帮助最大的一篇文章，大家好好看看
已经有46人回复
- 双语阅读——人人都应该学习的20个软技能
已经有14人回复
- 编辑告诉我返回一个审稿意见？猜猜是positive还是negative？
已经有9人回复
黄黄050607
木虫 (著名写手)
- 应助: 9 (幼儿园)
- 金币: 1763.2
- 红花: 4
- 帖子: 1402
- 在线: 280.7小时
- 虫号: 2285769
- 注册: 2013-02-18
- 性别: GG
- 专业: 人力资源管理
10楼2013-03-27 07:25:55
XiaOliAngeR
木虫 (小有名气)
- 应助: 45 (小学生)
- 金币: 2785.8
- 红花: 2
- 帖子: 211
- 在线: 148.9小时
- 虫号: 1943725
- 注册: 2012-08-17
- 性别: GG
- 专业: 药物分析
2楼2013-03-25 22:42:16
XiaOliAngeR
木虫 (小有名气)
- 应助: 45 (小学生)
- 金币: 2785.8
- 红花: 2
- 帖子: 211
- 在线: 148.9小时
- 虫号: 1943725
- 注册: 2012-08-17
- 性别: GG
- 专业: 药物分析
3楼2013-03-25 22:46:01
【答案】应助回帖
感谢参与，应助指数 +1
|
Negative Negative controls are groups where no phenomenon is expected. They ensure that there is no effect when there should be no effect. To continue with the example of drug testing, a negative control is a group that has not been administered the drug. We would say that the control group should show a negative or null effect. If the treatment group and the negative control both produce a negative result, it can be inferred that the treatment had no effect. If the treatment group and the negative control both produce a positive result, it can be inferred that a confounding variable acted on the experiment, and the positive results are likely not due to the treatment. [edit]Positive Positive controls are groups where a phenomenon is expected. That is, they ensure that there is an effect when there should be an effect, by using an experimental treatment that is already known to produce that effect (and then comparing this to the treatment that is being investigated in the experiment). Positive controls are often used to assess test validity. For example, to assess a new test's ability to detect a disease, then we can compare it against a different test that is already known to work. The well-established test is the positive control, since we already know that the answer to the question (whether the test works) is yes. Similarly, in an enzyme assay to measure the amount of an enzyme in a set of extracts, a positive control would be an assay containing a known quantity of the purified enzyme (while a negative control would contain no enzyme). The positive control should give a large amount of enzyme activity, while the negative control should give very low to no activity. If the positive control does not produce the expected result, there may be something wrong with the experimental procedure, and the experiment is repeated. For difficult or complicated experiments, the result from the positive control can also help in comparison to previous experimental results. For example, if the well-established disease test was determined to have the same effectiveness as found by previous experimenters, this indicates that the experiment is being performed in the same way that the previous experimenters did. When possible, multiple positive controls may be used - if there is more than one disease test that is known to be effective, more than one might be tested. Multiple positive controls also allow finer comparisons of the results (calibration, or standardization) if the expected results from the positive controls have different sizes. For example, in the enzyme assay discussed above, a standard curve may be produced by making many different samples with different quantities of the enzyme. From: http://en.wikipedia.org/wiki/Scientific_control |
5楼2013-03-25 23:08:08
20