语气比较的结果解释 [英] Interpreting results from emmeans comparison

问题描述

我有一个具有两个固定影响的glm模型，即处理"和日期"，用于根据时间序列中收集的数据估算温度.在处理"中，有三种不同的类别:悬钩子，毛圈布或对照，并且在这些遮篷下测量温度.像这样创建模型 mod1<-glm(Temp〜Treatment * Date，data = aveTerry.df)

I have a glm model with two fixed effects, Treatment and Date, to estimate Temperature from data collected in a time series. Within Treatment there are three different categories: Fucus, Terrycloth or Control, and temperature is measured beneath those canopies. The model is created like so mod1 <- glm(Temp ~ Treatment * Date, data = aveTerry.df )

我正试图说明Terrycloth是否具有与Fucus冠层相似的效果(即复制它).

I am trying to tell if Terrycloth has a similar effect as Fucus canopy (i.e. replicates it).

我找到了 emmeans 软件包，并相信它可以通过使用我的模型帮助我在治疗中的这些水平之间进行比较，并以此来找到估计的边际均值 terry.emmeans<-emmeans(modAllTerry，poly〜Treatment | Date)并通过 plot(terry.emmeans.average，comparison = TRUE)+ theme_bw()

I found the emmeans package and believe it could help me compare between these levels within treatment by using my model, and have used it as so to find the estimated marginal means terry.emmeans <- emmeans(modAllTerry, poly ~ Treatment | Date) and plotted the comparisons via plot(terry.emmeans.average, comparison = TRUE) +theme_bw()

将此输出链接给我.

我正在寻找一些帮助，以了解该图形输出是什么，尤其是比较究竟是什么(由红色箭头显示).我有些理解，蓝色框是一天中每种处理的温度平均值的置信区间(基于模型)，但是想知道如何进行比较吗?为什么有些日子里只有一个箭头??

I am looking for some help understanding what this graphical output is, especially what exactly are the comparisons (which are shown by the red arrows). I somewhat understand the that blue boxes are the confidence intervals for the mean value of temperature for each treatment on one day (based on model), but am wondering how is the comparison made? And why do some days only have a one sided arrow?

推荐答案

如 plot.emmGrid 文档中所述，比较箭头的创建方式是:如果和仅当它们各自的手段在所述水平上显着不同时.

As described in the documentation for plot.emmGrid, the comparison arrows are created in such a way that two arrows are disjoint if and only if their respective means are significantly different at the stated level.

该集合中的最低均值只有一个向右箭头，因为该均值将不会与任何较小的均值进行比较，从而无需使用向左箭头.由于类似的原因，最高均值只有一个向左的箭头.这些箭头没有定义时间间隔.他们的唯一目的是描绘比较.

The lowest mean in the set has only a right-pointing arrow because that mean will not be compared with anything smaller, obviating the need for a left-pointing arrow. For similar reasons, the highest mean has only a left-pointing arrow. These arrows do not define intervals; their only purpose is depicting comparisons.

在成对比较的SE差异很大的情况下，可能无法构建比较箭头.如果发生这种情况，则会显示一条错误消息.

In situations where the SEs of pairwise comparisons vary widely, it may not be possible to construct comparison arrows. If that happens, an error message is displayed.

也可以使用置信区间，但是不应将这些配置项用于比较均值.

Confidence intervals are available as well, but those CIs should not be used for comparing means.

更多信息和示例可以通过 vignette("comparisons"，"emmeans")找到.另外，在 vignette("xplanations"，"emmeans")

More information and examples may be found via vignette("comparisons", "emmeans"). Also, details of how the arrows are actually constructed are given in vignette("xplanations", "emmeans")

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