目前在全球眼科医疗器械市场中，外资品牌占据垄断地位，2017年全球前7大企业占据94.6%的市场份额。从国内市 场来看，我国眼科医疗器械行业市场集中度较低，企业竞争力普遍较弱，眼科高端市场主要为国际巨头企业所主导， 2019年中国眼科医疗器械市场前三大企业分别为诺华、伦博士和强生，市场份额占比分别为7.2%、6.8%、5.9%。在 “带量采购”与“两票制”等政策激励下，国产替代进口趋势明显，国内厂商或将乘势实现弯道超车。器械中，眼科器械设备主要是爱尔康以及蔡司等进口企业垄断，而在耗材领域，眼科耗材中诸如人工晶状体、角膜 塑形镜等受益国内庞大的需求以及消费升级，迎来快速增速。从2018年中国高值
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software used in this text is Stata, version 10 (StataCorp, 2007). It was chosen for the breadth and depth of its statistical methods, for its ease of use,
excellent graphics and excellent documentation. There are several other excellent packages available on the market. However, the aim of this text is to
teach biostatistics through a specific software package, and length restrictions make it impractical to use more than one package. If you have not
yet invested a lot of time learning a different package, Stata is an excellent
choice for you to consider. If you are already attached to a different package, you may still find it easier to learn Stata than to master or teach the
material covered here from other textbooks. The topics covered in this text
are linear regression, logistic regression, Poisson regression, survival analysis, and analysis of variance. Each topic is covered in two chapters: one
introduces the topic with simple univariate examples and the other covers more complex multivariate models. The text makes extensive use of a
number of real data sets. They all may be downloaded from my web site
at biostat.mc.vanderbilt.edu/dupontwd/wddtext/. This site also
contains complete log files of all analyses discussed in this text.
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