1

关于 lapply() 在模拟研究中的应用,我碰壁了。这些数据旨在帮助我们了解标准化公式如何影响提案评级活动的结果。

评估者需要满足三个条件:无偏见、统一偏见(评估者之间的偏见增加)和双向偏见(评估者之间的偏见是正负平衡)。

假设提案的真实价值是已知的。

我们希望在每个偏差条件下生成一组复制数据集,以便数据集模拟单个提案评估期(面板)。然后,我们想复制面板来模拟有许多提案评估期。

数据结构示意图如下:

 The data structure looks like this:

 p = number of proposals
 r = number of raters

 n.panels = number of replicate panels

 t.reps = list of several replicate panels

 three bias conditions:     n.bias - no bias
                            u.bias - uniform bias (raters higher than previous rater)
                            b.bias - bidirectional bias (balanced up and down bias)


 -|
 t     1        |..| --> 10*(n.bias(p*r)) + 10*(u.bias(p*r)) + 10*(b.bias(p*r)  {panel replication 1}
 .     2        |..| --> 10*(n.bias(p*r)) + 10*(u.bias(p*r)) + 10*(b.bias(p*r)  {panel replication 2}
 r     :                    :                         :               :                  :
 e     :                    :                         :               :                  :
 p     n.panels |..| --> 10*(n.bias(p*r)) + 10*(u.bias(p*r)) + 10*(b.bias(p*r)  {n. panels replications}
 s      
 _|

以下 R 代码正确生成数据:

##########  start of simulation parameters

set.seed(271828)

means <- matrix(c(rep(50,3), rep(60,3), rep(70,4) ), ncol = 1)      #  matrix of true proposal values
bias.u <- matrix(c(0,2,4,6,8), nrow=1)                              #  unidirectional bias
bias.b <- matrix(c(0,3,-3, 5, -5), nrow=1)                          #  bidirectional bias   


ones.u <- matrix(rep(1,ncol(bias.u)), nrow = 1)                 #  number of raters is the number of columns  (r)
ones.b <- matrix(rep(1,ncol(bias.b)), nrow = 1)
ones.2 <- matrix(rep(1,nrow(means)),  ncol = 1)                 #  number of proposals is the number of rows  (p)

true.ratings <- means%*%ones.u                                  #  gives matrix of true proposal value for each rater (p*r)
uni.bias    <- ones.2%*%bias.u
bid.bias    <- ones.2%*%bias.b                                  #  gives matrix of true rater bias for each proposal  (p*r)

n.val <- nrow(means)*ncol(ones.u)

#   true.ratings
#   uni.bias
#   bid.bias



library(MASS)



#####
#####  generating replicate data...
#####

##########--------------------  analyzing mse of adjusted scores across replications

##########--------------------  developing random replicates of panel data

##########-----  This means that there are (reps) replications in each of the bias conditions
##########-----  to represent a plausible set of ratings in a particular collection 
##########-----  of panels. So for one proposal cycle (panel) , there are 3 * (reps) * nrow(means) 
##########-----  number of proposal ratings.
##########-----
##########-----  There are (n.panels) replications of the total number of proposal ratings placed in a list
##########-----  (t.reps).



n.panels <- 2    #  put in the number of replicate panels that should be produced
reps     <- 10   #  put in the number of times each bias condition should be included in a panel

t.reps <- list()

n.bias <- list()
u.bias <- list()
b.bias <- list()




for (i in 1:n.panels)

    {
        {
            for(j in 1:reps) 
                n.bias[[j]] <- true.ratings + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means)) 
            for(j in 1:reps)    
                u.bias[[j]] <- true.ratings + uni.bias + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means))
            for(j in 1:reps)
                b.bias[[j]] <- true.ratings + bid.bias + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means))
        }

    t.reps[[i]] <- list(n.bias, u.bias, b.bias)

    }


# t.reps

列表中的每个元素 (t.reps) 都是对整个提案集的评审小组的随机复制。

我想应用以下功能来“调整”面板内的分数,使用整个提案分数集(跨所有评估者和提案)的特征来调整评估者的值。这个想法是以一种或另一种方式纠正任何偏见(例如,在评估提案时过于苛刻或过于简单)。

应该对每个(reps)数据集应用调整。

因此,对于一个面板,将有 30 个重复数据集(每个偏差条件 10 个),每个重复数据集将有 10 个由 5 个评估者评级的提案,总共有 300 个提案。

因此,想法是进行随机复制,以了解调整后的分数与未调整的分数相比如何。

我曾尝试在 (t.reps) 列表中的列表中使用 lapply() 函数,但它不起作用。

adj.scores <- function(x, tot.dat)
    {
    t.sd <- sd(array(tot.dat))
    t.mn <- mean(array(tot.dat))

    ones.t.mn <- diag(1,ncol(x))

    p <- nrow(x)
    r <- ncol(x)

    ones.total <- matrix(1,p,r)

    r.sd <- diag(apply(x,2, sd))
    r.mn <- diag(apply(x,2, mean))


    den.r.sd <- ginv(r.sd)
    b.shift <- x%*%den.r.sd

    a <- t.mn*ones.t.mn - den.r.sd%*%r.mn
    a.shift <- ones.total%*%a


    l.x <- b.shift + a.shift

    return(l.x)

    }

##########  I would like to do something like this...

##########  apply the function to each element in the list t.reps


dat.1 <- matrix(unlist(t.reps[[1]]), ncol=5)
adj.rep.1 <- lapply(t.reps[[1]], adj.scores, tot.dat = dat.1)

我对其他方法/解决方法持开放态度,这些方法/解决方法将允许使用来自整个评级集的统计数据在一组提案评级中调整评级者。可能有一些我不知道或没有遇到过的 R 功能。

此外,如果有人可以推荐一本书来编写这样的数据结构(在 R、Perl 或 Python 中),那将不胜感激。到目前为止,我发现的文本并没有详细解决这些问题。

非常非常感谢提前。

-乔恩

4

2 回答 2

1

我不能说我完全理解整个问题(我不是统计员!),但是你的 lapply 行失败的原因是当它需要一个矩阵时adj.scores得到一个列表。x

由于您有列表列表(列表!),因此rapply似乎更合适。以下似乎产生了一些合理的东西:

adj.rep.1 <- rapply(t.reps[[1]], adj.scores, how='replace', tot.dat = dat.1)

# comparing the structures
str(t.reps[[1]])
str(adj.rep.1)

希望这可以帮助!

于 2011-07-22T16:42:04.490 回答
0

我很晚才发布对我有用的解决方案。我相信可以进行改进,所以请随时发表评论!

本练习的目的是了解提案评级的线性变换对提案选择的影响程度。这个想法是试图将“提案质量”与“评估者偏见”和“小组偏见”分开。

做到这一点的一种方法本质上是将所有评级集中在面板均值上,然后使用所有评级的整体均值和 sd 对以面板为中心的评级进行均值 / sd 转换。这个程序在函数中adj.scores

这是不平凡的,因为提案是由人评估的,并且可能会有大量的经济激励依赖于成功的提案评估(赠款、合同等)。

欢迎任何关于改进或竞争策略的想法。

####################
##########  proposal ratings project
##########  17 June 2011
##########  original code by:  jjb with help from es



##########------  functions to be read in and called when desired

##########  applying  this function to a single matrix will give detailed output 
##########  calculating generalizability theory components
##########  not a very robust formulation, but a good place to start
##########  for future, put panel facet on this design

    g.pxr.long = function(x)
     {
      m.raters <<- colMeans(x)
      n.raters <<- length(m.raters)

      m.props <<-  rowMeans(x)
      n.props <<-  length(m.props)

      m.total <<-  mean(x)
      n.total <<-  nrow(x)*ncol(x)

      m.raters.2 <<- m.raters^2
      m.props.2 <<- m.props^2

      sum.m.raters.2 <<- sum(m.raters.2)
      sum.m.props.2  <<- sum(m.props.2)

      ss.props <<- n.raters*(sum.m.props.2) - n.total*(m.total^2)
      ss.raters <<- n.props*(sum.m.raters.2) - n.total*(m.total^2)
      ss.pr  <<-  sum(x^2) - n.raters*(sum.m.props.2) - n.props*(sum.m.raters.2) +  n.total*(m.total^2)

      df.props <- n.props - 1
      df.raters <- n.raters - 1
      df.pr  <-  df.props*df.raters

      ms.props <- ss.props / df.props
      ms.raters <- ss.raters / df.raters
      ms.pr <- ss.pr / df.pr

      var.p <- (ms.props - ms.pr) / n.raters
      var.r <- (ms.raters - ms.pr) / n.props
      var.pr <- ms.pr


      out.1 <- as.data.frame( matrix(c( df.props, df.raters, df.pr, 
                                        ss.props, ss.raters, ss.pr, 
                                        ms.props, ms.raters, ms.pr,  
                                        var.p, var.r, var.pr), ncol = 4))

      out.2 <- as.data.frame(matrix(c("p", "r", "pr" ), ncol = 1))
      g.out.1 <- as.data.frame(cbind(out.2, out.1))
      colnames(g.out.1) <- c("   source", "   df  ", "   ss  ", "   ms  ", "   variance")



     var.abs <- (var.r / n.raters) + (var.pr / n.raters)
     var.rel <- (var.pr / n.raters)
     var.xbar <- (var.p / n.props) + (var.r / n.raters) + (var.pr / (n.raters*n.props) )

     gen.coef <- var.p / (var.p + var.rel)
     dep.coef <- var.p / (var.p + var.abs)

     out.3 <- as.data.frame(matrix(c(var.rel, var.abs, var.xbar, gen.coef, dep.coef), ncol=1))
     out.3 <- round(out.3, digits = 4)
     out.4 <- as.data.frame(matrix(c("relative error variance", "absolute error variance", "xbar error variance", "E(rho^2)", "Phi"), ncol=1))

     g.out.2 <- as.data.frame(cbind(out.4,out.3))
     colnames(g.out.2) <- c("   estimate ", "   value")

    outs <- list(g.out.1, g.out.2)
    names(outs) <- c("generalizability theory: G-study components", "G-study Indices")
    return(outs)

     }

##########-----  calculating confidence intervals using Chebychev, Cramer, and Normal   

##########-----  use this to find alpha for desired k

factor.choose = function(k)

    {
    alpha <- 1 / k^2
    return(alpha)   
    }




conf.intervals = function(dat, alpha)
    {   



    k <- sqrt( 1 / alpha )  # specifying what the k factor is...

    x.bar <- mean(dat)
    x.sd  <- sd(dat)

    n.obs <- length(dat)

    sem <- x.sd / sqrt(n.obs)

    ub.cheb <- x.bar + k*sem
    lb.cheb <- x.bar - k*sem

    ub.crem <- x.bar + (4/9)*k*sem
    lb.crem <- x.bar - (4/9)*k*sem

    ub.norm <- x.bar + qnorm(1-alpha/2)*sem
    lb.norm <- x.bar - qnorm(1-alpha/2)*sem

    out.lb <- matrix(c(lb.cheb,  lb.crem,  lb.norm), ncol=1)
    out.ub <- matrix(c(ub.cheb,  ub.crem, ub.norm), ncol=1)


    dat <- as.data.frame(dat)

    mean.raters <- as.matrix(rowMeans(dat))

    dat$z.values <- matrix((mean.raters - x.bar) / x.sd)

    select.cheb <- dat[ which(abs(dat$z.values) >= k ) , ]

    select.crem <- dat[ which(abs(dat$z.values) >= (4/9)*k ) , ]

    select.norm <- dat[ which(abs(dat$z.values) >=  qnorm(1-alpha/2)) , ]

    count.cheb <- nrow(select.cheb)
    count.crem <- nrow(select.crem)
    count.norm <- nrow(select.norm)

    out.dat <- list()

    out.dat <- list(select.cheb, select.crem, select.norm)
    names(out.dat) <- c("Selected cases: Chebychev", "Selected cases: Cramer's", "Selected cases: Normal")



    out.sum <- matrix(c(x.bar, x.sd, n.obs), ncol=3)
    colnames(out.sum) <- c("mean", "sd", "n")

    out.crit <- matrix(c(alpha, k, (4/9)*k, qnorm(1-alpha/2)) ,ncol=4 )
    colnames(out.crit) <- c("alpha", "k", "(4/9)*k", "z" )

    out.count <- matrix(c(count.cheb, count.crem, count.norm) ,ncol=3 )
    colnames(out.count) <- c("Chebychev", "Cramer" , "Normal")
    rownames(out.count) <- c("count")


    outs <- list(out.sum, out.crit, out.count, out.dat)
    names(outs) <- c("Summary of data", "Critical values", "Count of Selected Cases", "Selected Cases")

    return(outs)




    }


rm(list = ls())


set.seed(271828)

means <- matrix(c( rep(50,19), rep(70,1) ), ncol = 1)      #  matrix of true proposal values
bias.u <- matrix(c(0,2,4), nrow=1)                                  #  unidirectional bias
bias.b <- matrix(c(0,5, -5), nrow=1)                                #  bidirectional bias   


ones.u <- matrix(rep(1,ncol(bias.u)), nrow = 1)                 #  number of raters is the number of columns  (r)
ones.b <- matrix(rep(1,ncol(bias.b)), nrow = 1)
ones.2 <- matrix(rep(1,nrow(means)),  ncol = 1)                 #  number of proposals is the number of rows  (p)

true.ratings <- means%*%ones.u                                  #  gives matrix of true proposal value for each rater (p*r)
uni.bias    <- ones.2%*%bias.u
bid.bias    <- ones.2%*%bias.b                                  #  gives matrix of true rater bias for each proposal  (p*r)


pan.bias.pos <- matrix(20,nrow=nrow(true.ratings), ncol=ncol(true.ratings))  #  gives a matrix of bias for every member in a panel (p*r)



n.val <- nrow(true.ratings)*ncol(true.ratings)

#   true.ratings
#   uni.bias
#   bid.bias
#   pan.bias.pos



library(MASS)



#####
#####  generating replicate data...
#####




n.panels <- 10      #  put in the number of replicate panels that should be produced
reps     <- 2        #  put in the number of times each bias condition should be included in a panel 

t.reps <- list()

n.bias <- list()
u.bias <- list()
b.bias <- list()
pan.bias <- list()

n.bias.out <- list()
u.bias.out <- list()
b.bias.out <- list()
pan.bias.out <- list()


for (i in 1:n.panels)

    {
        {
            for(j in 1:reps) 
                n.bias[[j]] <- true.ratings + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means)) 
            for(j in 1:reps)    
                u.bias[[j]] <- true.ratings + uni.bias + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means))
            for(j in 1:reps)
                b.bias[[j]] <- true.ratings + bid.bias + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means))

        }   

        pan.bias[[i]]  <- true.ratings + pan.bias.pos + matrix(round(rnorm(n.val,4,2), digits=0), nrow = nrow(means))

        n.bias.out[[i]] <- n.bias
        u.bias.out[[i]] <- u.bias
        b.bias.out[[i]] <- b.bias

        t.reps[[i]] <- c(n.bias, u.bias, b.bias, pan.bias[i])

    }

#  t.reps


#  rm(list = ls())



##########-----  this is the standardization formula to be applied to proposal ratings **WITHIN** a panel

adj.scores <- function(x, tot.dat)

    {
    t.sd <- sd(array(tot.dat))
    t.mn <- mean(array(tot.dat))

    ones.t.mn <- diag(1,ncol(x))

    p <- nrow(x)
    r <- ncol(x)

    ones.total <- matrix(1,p,r)

    r.sd <- diag(apply(x,2, sd))
    r.mn <- diag(apply(x,2, mean))


    den.r.sd <- ginv(r.sd)
    b.shift <- x%*%den.r.sd

    a <- t.mn*ones.t.mn - den.r.sd%*%r.mn
    a.shift <- ones.total%*%a


    l.x <- b.shift + a.shift

    return(l.x)
    }



##########-----  applying standardization formula and getting 
##########-----  proposal means for adjusted and unadjusted ratings

adj.rep <- list()
m.adj <- list()
m.reg <- list()

for (i in 1:n.panels)

    {

    panel.data <- array(unlist(t.reps[[i]]))

    adj.rep[[i]] <- lapply(t.reps[[i]], adj.scores, tot.dat = panel.data)

    m.adj[[i]] <- lapply(adj.rep[[i]], rowMeans)
    m.reg[[i]] <- lapply(t.reps[[i]], rowMeans)

    }









##########----- 
##########-----  This function extracts the replicate proposal means for each set of reviews    
##########-----  across panels.  So, if there are 8 sets of reviewers that are simulated 10 times, 
##########-----  this extracts the first set of means across the 10 replications and puts them together,
##########-----  and then extracts the second set of means across replications and puts them together, etc..
##########-----  The result will be 8 matrices made up of 10 columns with rows .
##########-----  



##########-----  first for unadjusted means 





means.reg <- matrix(unlist(m.reg), nrow=nrow(means))
sets <- length(m.reg[[1]])
counter <- n.panels*length(m.reg[[1]])


m.reg.panels.set <- list()

        for (j in 1:sets)

            {
                m.reg.panels.set[[j]] <- means.reg[ , c(seq( j, counter, sets))]

            }






##########-----  now for adjusted means


means.adj <- matrix(unlist(m.adj), nrow=nrow(means))
sets <- length(m.adj[[1]])
counter <- n.panels*length(m.adj[[1]])


m.adj.panels.set <- list()

        for (j in 1:sets)

            {
                m.adj.panels.set[[j]] <- means.adj[ , c(seq( j, counter, sets))]

            }    



##########   calculating msd as bias^2 and error^2




msd.calc <- function(x)
        {

            true.means  <- means
            calc.means  <- as.matrix(rowMeans(x))


            t.means.mat <- matrix(rep(true.means, n.panels), ncol=ncol(x))
            c.means.mat <- matrix(rep(calc.means, n.panels), ncol=ncol(x))

            msd <- matrix( rowSums( (x - t.means.mat )^2) / ncol(c.means.mat) )
            bias.2 <- (calc.means - true.means)^2
            e.var <-  matrix( rowSums( (x - c.means.mat )^2) / ncol(c.means.mat ) )

            msd <- matrix(c(msd, bias.2, e.var), ncol = 3)
            colnames(msd) <- c("msd", "bias^2", "e.var")

            return(msd)

        }


##########  checking work...

#       msd.calc <- bias.2 + e.var
#       all.equal(msd, msd.calc)


##########-----  applying function to each set across panels        

msd.reg.panels <- lapply(m.reg.panels.set, msd.calc)        

msd.adj.panels <- lapply(m.adj.panels.set, msd.calc)

msd.reg.panels
msd.adj.panels        

##########  for the unadjusted scores, the msd is very large (as is expected)
##########  for the adjusted scores, the msd is in line with the other panels






##########-----  trying to evaluate impact of adjusting scores on proposal awards



reg.panel.1 <- matrix(unlist(m.reg[[1]]), nrow=nrow(means))
adj.panel.1 <- matrix(unlist(m.adj[[1]]), nrow=nrow(means))


reg <- matrix(array(reg.panel.1), ncol=1)
adj <- matrix(array(adj.panel.1), ncol=1)

panels.1 <- cbind(reg,adj)

colnames(panels.1) <- c("unadjusted", "adjusted")

cor(panels.1, method="spearman")

plot(panels.1)
########   identify(panels.1)


plot(panels.1, xlim = c(25,95), ylim = c(25,95) )
abline(0,1, col="red")


##########  the adjustment greatly reduces variances of ratings 
##########  compare the projection of the panel means onto the respective margins



##########-----  examining the selection of the top 10% of the proposals


pro.names <- matrix(seq(1,nrow(reg),1))

df.reg <- as.data.frame(cbind(pro.names, reg))
colnames(df.reg) <- c("pro", "rating")
df.reg$q.pro <- ecdf(df.reg$rating)(df.reg$rating) 


df.adj <- as.data.frame(cbind(pro.names, adj))
colnames(df.adj) <- c("pro", "rating")
df.adj$q.pro <- ecdf(df.adj$rating)(df.adj$rating)


awards.reg <- df.reg[ which(df.reg$q.pro >= .90) , ]
awards.adj <- df.adj[ which(df.adj$q.pro >= .90) , ]


awards.reg[order(-awards.reg$q.pro) , ]
awards.adj[order(-awards.adj$q.pro) , ]


awards.reg[order(-awards.reg$pro) , ]
awards.adj[order(-awards.adj$pro) , ]


#####  using unadjusted scores, the top 10% of proposals come mostly from one (biased) panel, and the rest are made up of the 
#####  highest scoring proposal (from the biased rater) from the remaining panels.

#####  using the adjusted scores, the top 10% of proposals are made up of the highest scoring proposal (the biased rater) from the 
#####  several panels, and a few proposals from other panels.  Doesn't seem to be a systematic explanation as to why...




#########-----  treating rating data in an ANOVA model


ratings <- do.call("rbind", t.reps[[1]] )
panels <- factor(gl(7,20))



fit <- manova(ratings ~ panels)
summary(fit, test="Wilks")




adj.ratings <- do.call("rbind", adj.rep[[1]] )
adj.fit <- manova(adj.ratings ~ panels)
summary(adj.fit, test="Wilks")


##########-----  thinking... extra ideas for later

##########-----  calculating Mahalanobis distance to identify biased panels

mah.dist = function(dat)
        {md.dat <- as.matrix(mahalanobis(dat, center = colMeans(dat) , cov = cov(dat) ))
         md.pv <- as.matrix(pchisq(md.dat, df = ncol(dat), lower.tail = FALSE))

        out <- cbind(md.dat, md.pv)

        out.2 <- as.data.frame(out)
        colnames(out.2) <- c("MD", "pMD")


        return(out.2)
        }



mah.dist(ratings)

mah.dist(adj.ratings)
于 2012-03-08T15:40:44.217 回答