casecross(season)
casecross()所属R语言包：season
Case–crossover analysis to control for seasonality
病例交叉分析来控制的季节性
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Fits a time-stratified case–crossover to regularly spaced time series data. The function is not suitable for irregularly spaced individual data. The function only uses a time-stratified design, and other designs such as the symmetric bi-directional design, are not available.
适合时间分层的病例交叉定期间隔的时间序列数据。该函数是不适合的不规则间隔的单个数据。的功能只使用了的时间分层设计，双向对称设计等其他设计，是不可用的。
用法----------Usage----------
参数----------Arguments----------
参数：formula
formula. The dependent variable should be an integer count (e.g., daily number of deaths).
公式。因变量应该是一个整型数（例如，每天的死亡人数）。
参数：data
data set as a data frame.
作为数据框的数据集。
参数：exclusion
exclusion period (in days) around cases, set to 2 (default). Must be positive and smaller than stratalength.
排除期间（天）左右的情况下，设置为2（默认值）。必须小于stratalength。
参数：stratalength
length of stratum in days, set to 28 (default).
天，地层长度设置为28（默认值）。
参数：matchdow
match case and control days using day of the week (TRUE/default=FALSE). This matching is in addition to the strata matching.
病例组和对照天是星期几（TRUE /默认值= FALSE）相匹配。这种匹配是在除了地层匹配。
参数：usefinalwindow
use the last stratum in the time series, which is likely to contain less days than all the other strata (TRUE/default=FALSE).
使用最后一个阶层中的时间序列，这很可能是含有较少的天数比所有其他阶层（TRUE /默认值= FALSE）。
参数：matchconf
match case and control days using an important confounder (optional; must be in quotes). matchconf is the variable to match on. This matching is in addition to the strata matching.
与病例组和对照天使用的一个重要的影响因子（可选，必须用引号括起来）。 matchconf是匹配的变量。这种匹配是在除了地层匹配。
参数：confrange
range of the confounder within which case and control days will be treated as a match (optional). Range = matchconf (on case day) +/- confrange.
范围内将被视为匹配（可选）病例组和对照天的混杂因素。范围=matchconf情况下，每天+/-confrange。
参数：stratamonth
use strata based on months, default=FALSE. Instead of a fixed strata size when using stratalength.
使用基于个月的地层，默认值= FALSE。而不是一个固定的阶层大小时使用stratalength。
Details
详细信息----------Details----------
The case–crossover method compares “case” days when events occurred (e.g., deaths) with control days to look for differences in exposure that might explain differences in the number of cases. Control days are selected to be nearby to case days, which means that only recent changes in the independent variable(s) are compared. By only comparing recent values, any long-term or seasonal variation in the dependent and independent variable(s) can be eliminated. This elimination depends on the definition of nearby and on the seasonal and long-term patterns in the independent variable(s).
的情况下，交叉的方法比较“案例”事件发生时（例如，死亡人数）与控制天中暴露的差异，这或许可以解释差异的情况下看。控制天被选为附近的情况下，天，这意味着，只有最近的独立变量（S）的变化进行比较。通过只比较近期的值，在依赖和独立的变量（S），可以消除任何术语或季节性变化。这消除依赖于附近的季节性和术语的独立变量（S）模式的定义。
Control and case days are only compared if they are in the same stratum. The stratum is controlled by stratalength, the default value is 28 days, so that cases and controls are compared in four week sections. Smaller stratum lengths provide a closer control for season, but reduce the available number of controls. Control days that are close to the case day may have similar levels of the independent variable(s). To reduce this correlation it is possible to place an exclusion around the cases. The default is 2, which means that the smallest gap between a case and control will be 3 days.
控制和案例的日子相比，如果他们是在同一地层。地层控制stratalength，默认值是28天，因此，病例组和对照组相比，在四个星期的部分。更小的地层长度为赛季提供了更严密的控制，但减少的可用数量的控制。控制天数是接近的情况下，一天可能也有类似的独立变量（S）。为了减少这种相关性，它可以放置一个exclusion周围的情况下。缺省值是2，这意味着最小的差距的情况下，控制将是3天。
To remove any confounding by day of the week it is possible to additionally match by day of the week (matchdow), although this often reduces the number of available controls. This matching is in addition to the strata matching.
要删除任何干扰，星期几可以另外搭配星期几（matchdow），尽管这通常会减少可用的控件。这种匹配是在除了地层匹配。
It is possible to additionally match case and control days by an important confounder (matchconf) in order to remove its effect. Control days are matched to case days if they are: i) in the same strata, ii) have the same day of the week if matchdow=TRUE, iii) have a value of matchconf that is within \pm confrange of the value of matchconf on the case day. If the range is set too narrow then the number of available controls will become too small, which in turn means the number of case days with at least one control day is compromised.
这是可能的，另外一个重要的影响因子（matchconf），以消除其效果相匹配的病例组和对照天。控制天数相匹配的情况下，天，如果他们是：i）在同一个阶层，二）具有相同的星期几，如果matchdow=TRUE，三）有值的matchconf内\pmconfrange的价值matchconf的情况下当天的。如果过于狭窄的范围内被设置，那么可用的控件的数目将变得过小，这反过来又意味着受到损害的数目的情况下与至少一个控制天天。
The method uses conditional logistic regression (see coxph and so the parameter estimates are odds ratios.)
该方法采用条件Logistic回归分析（见coxph等参数估计比值比。）
The code assumes that the data frame contains a date variable (in Date format) called "date".
该代码假定数据框包含日期变量（Date格式），被称为“日”。
值----------Value----------
参数：call
the original call to the casecross function.
的原始呼叫的casecross函数。
参数：c.model
conditional logistic regression model of class coxph.
条件Logistic回归模型类coxph。
参数：ncases
total number of cases.
情况的总数。
参数：ncasedays
number of case days with at least one control day.
的情况下，天数至少有一个控制的一天。
参数：ncontroldayss
average number of control days per case day.
控制的情况下，一天的天数的平均数。
（作者）----------Author(s)----------
Adrian Barnett <a href="mailto:a.barnett<at>qut.edu.au">a.barnett<at>qut.edu.au</a>
参考文献----------References----------
Referent selection strategies and their implications for bias. Epidemiology 16(6), 717–726.
<h3>See Also</h3>
实例----------Examples----------
# cardiovascular disease data[心血管疾病数据]
data(CVDdaily)
CVDdaily=subset(CVDdaily,date<=as.Date('1987-12-31')) # subset for example[例如子集]
# Effect of ozone on CVD death[臭氧对心血管疾病死亡的影响]
model1 = casecross(cvd ~ o3mean+tmpd+Mon+Tue+Wed+Thu+Fri+Sat, data=CVDdaily)
summary(model1)
# match on day of the week[匹配上的一周的天]
model2 = casecross(cvd ~ o3mean+tmpd,matchdow=TRUE, data=CVDdaily)
summary(model2)
# match on temperature to within a degree[在一定程度内的温度相匹配]
model3 = casecross(cvd ~ o3mean+Mon+Tue+Wed+Thu+Fri+Sat, data=CVDdaily,
matchconf='tmpd', confrange=1)
summary(model3)
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-9-29 23:48:08
