bison(TwoStepCLogit)
bison()所属R语言包：TwoStepCLogit
Bison data
野牛数据
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Bison data collected in Prince Albert National Park, Saskatchewan, Canada (Craiu et al. 2011).
野牛收集的数据，加拿大，萨斯喀彻温省阿尔伯特王子国家公园（Craiu等，2011）。
格式----------Format----------
A data frame with 16818 observations on the following 10 variables.
16818以下10个变量的观察数据框。
Cluster pair of animals (dyad) ID
聚类对动物（对子）ID
Strata stratum ID
地层地层ID
Y response variable: 1 for visited locations, 0 otherwise
Ÿ响应变量前往的地方：1，否则为0
water land cover indicator covariate: 1 for water, 0 otherwise
水土地覆盖指标协：水= 1，否则为0
agric land cover indicator covariate: 1 for agricultural locations , 0 otherwise
农耕土地覆盖指标协：农业位置1，否则为0
forest land cover indicator covariate: 1 for forests, 0 otherwise
森林土地覆盖指标协：1，森林，否则为0
meadow land cover indicator covariate: 1 for meadows, 0 otherwise
草甸土地覆盖指标协：1，草地，否则为0
biomass continuous covariate: above-ground vegetation biomass index measured
生物质连续协变量：地面植被生物量指数测定
pmeadow continuous covariate: the proportion of meadow in a circular plot
pmeadow连续协的比例草甸，在一个圆形的图
Details
详细信息----------Details----------
This data set was collected in order to study habitat selection by groups of free-ranging bison. For each observed group, two individuals (dyad) equipped with GPS radio-collars were followed simultaneously. A cluster is defined here as a pair of bison. This data set contains 20 clusters. The number of strata per cluster varies between 13 and 345 for a total of 1410 strata. A stratum is composed of two visited GPS locations (one for each individual) gathered at the same time, together with 10 random locations (five drawn within 700 m of each of the two focal bison). Therefore, there are 12 observations per stratum, with 2 cases (Y=1) and 10 controls (Y=0). However, due to problems in the data collection, 17 of the 1410 strata have only 6 observations (1 case and 5 controls).
为了研究组自由放养的野牛栖息地选择的，该数据集收集。对于每一个观察组，两个人（对子）配备了GPS无线电项圈同时随访。这里被定义为一对野牛的聚类。该数据集包含20个聚类。每个聚类的地层的数量在13和345之间变化为共1410地层。层数为是由两个访问GPS位置（一个用于每个单独的）聚集在同一时间，连同10的随机位置（5 700 m的每一个的两个焦点野牛内绘制）。因此，有12个每阶层的意见，有2例（Y = 1）和10名对照（Y = 0）。然而，由于数据的采集，17 1410地层中存在的问题，只有6个观察（1例和5）。
参考文献----------References----------
(2011), Conditional Logistic Regression with Longitudinal Follow-up and Individual-Level Random Coefficients: A Stable and Efficient Two-Step Estimation Method, Journal of Computational and Graphical Statistics. 20(3), 767-784.
实例----------Examples----------
data(bison)
# Some descriptive statistics about the data set:[一些描述性统计的数据集：]
ddim(formula = Y ~ strata(Strata) + cluster(Cluster), data = bison)
# Model 1: covariates meadow, biomass and biomass^2[模式1：协变量草甸，生物量和生物量^ 2]
# Random effects in front of biomass and biomass^2[在前面的生物量和生物量^ 2的随机效应]
# Main diagonal covariance structure for D[主对角线协方差结构为D]
Fit1 <- Ts.estim(formula = Y ~ meadow + biomass + I(biomass^2) +
strata(Strata) + cluster(Cluster), data = bison,
random = ~ biomass + I(biomass^2), all.m.1=FALSE, D="UN(1)")
Fit1
# Model 2: only covariates biomass and biomass^2[模式2：协变量的生物量和生物量^ 2]
# Random effects in front of biomass and biomass^2[在前面的生物量和生物量^ 2的随机效应]
# Main diagonal covariance structure for D[主对角线协方差结构为D]
Fit2 <- Ts.estim(formula = Y ~ biomass + I(biomass^2) + strata(Strata) +
cluster(Cluster), data = bison, all.m.1=FALSE, D="UN(1)")
Fit2
# Results reported in Table 2 of Craiu et al. (2011).[结果报告于表2中的Craiu等。 （2011年）。]
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注：
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发表于 2012-10-1 13:15:50
