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Who.cites.equator.Rmd
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Who.cites.equator.Rmd
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---
title: "Can we use EQUATOR citations to make a league table of good research practice?"
author: "Adrian Barnett & David Moher"
date: "`r format(Sys.time(), '%d %B %Y')`"
output: word_document
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, warning=FALSE, message=FALSE, comment='', dpi=400)
options(width=200)
options(scipen=999) # no scientific numbers
library(R2WinBUGS)# for clustering
library(mclust, quietly=TRUE) # for alternative clustering
library(dplyr)
library(readxl)
library(BlandAltmanLeh)
library(tables)
#library(doBy)
library(reshape2)
library(ggplot2)
cbbPalette <- c("#000000", "#E69F00", "#56B4E9", "#009E73", "#F0E442", "#0072B2", "#D55E00", "#CC79A7")
library(gridExtra) # for side-by-side plots
library(pander)
panderOptions('table.emphasize.rownames', FALSE)
panderOptions('keep.trailing.zeros', TRUE)
panderOptions('table.split.table', Inf)
panderOptions('table.split.cells', Inf)
panderOptions('big.mark',',')
load('THE.RData') # from THE.data.R
load('Papers.for.Analysis.RData') # from data.management.R
load('pubmed.frame.RData') #
# function for mode
Mode <- function(x) {
ux <- unique(x)
ux[which.max(tabulate(match(x, ux)))]
}
# function to round with trailing zeros
roundz = function(x, digits=0){formatC( round( x, digits ), format='f', digits=digits)}
# rentrez library and API key
library(rentrez)
my.api.key = 'a0f7ea81742e357682051e951dcb7ffb5608' # generated on 15 November 2018, login here to check https://www.ncbi.nlm.nih.gov/myncbi/
set_entrez_key(my.api.key)
```
Our overall aim is to examine if international league tables of institutions could be updated to include a metric of good research practice, and we consider citing an EQUATOR guideline to indicate good practice. We used the CONSORT (randomised trials), PRISMA (systematic reviews) and STROBE (observational) checklists.
We used `r nrow(pubmed.frame)` papers from the journals below.
##### CONSORT
```{r consort.papers, results='asis'}
# bullet list
pubmed.frame$title = as.character(pubmed.frame$title)
pubmed.frame$journal = as.character(pubmed.frame$journal)
pubmed.frame$journal = gsub('=',':', pubmed.frame$journal) # replace tricky character
to.list = subset(pubmed.frame, type=='CONSORT')
for (k in 1:nrow(to.list)){
cat('* ', to.list$title[k], ', _', to.list$journal[k], '_ (', to.list$year[k], ')\n', sep='')
}
# output to latex
zz = file('latex.paper.list.txt','w')
cat('CONSORT\n\\begin{itemize}\n', file=zz)
for (k in 1:nrow(to.list)){
cat('\\item ', to.list$title[k], ', \\textit{', to.list$journal[k], '} (', to.list$year[k], '), PMID=', to.list$pmid[k],'\n', sep='', file=zz)
}
cat('\\end{itemize}\n', file=zz)
close(zz)
```
##### PRISMA
```{r primsa.papers, results='asis'}
# bullet list
to.list = subset(pubmed.frame, type=='PRISMA')
for (k in 1:nrow(to.list)){
cat('* ', to.list$title[k], ', _', to.list$journal[k], '_ (', to.list$year[k], ')\n', sep='')
}
# output to latex
zz = file('latex.paper.list.txt','a') # append
cat('\nPRISMA\n\\begin{itemize}\n', file=zz)
for (k in 1:nrow(to.list)){
cat('\\item ', to.list$title[k], ', \\textit{', to.list$journal[k], '} (', to.list$year[k], '), PMID=', to.list$pmid[k],'\n', sep='', file=zz)
}
cat('\\end{itemize}\n', file=zz)
close(zz)
```
##### STROBE
```{r strobe.papers, results='asis'}
# bullet list
to.list = subset(pubmed.frame, type=='STROBE')
for (k in 1:nrow(to.list)){
cat('* ', to.list$title[k], ', _', to.list$journal[k], '_ (', to.list$year[k], ')\n', sep='')
}
# output to latex
zz = file('latex.paper.list.txt','a') # append
cat('\nSTROBE\n\\begin{itemize}\n', file=zz)
for (k in 1:nrow(to.list)){
cat('\\item ', to.list$title[k], ', \\textit{', to.list$journal[k], '} (', to.list$year[k], '), PMID=', to.list$pmid[k],'\n', sep='', file=zz)
}
cat('\\end{itemize}\n', file=zz)
close(zz)
```
#### Inclusion criteria
The inclusion criteria for our citing papers were:
* Articles or Reviews, in order to remove editorials, commentaries, corrections, etc.
* Published in 2016 or 2017 because league tables are based on annual data
To only include papers that adhered to the first item on the PRIMSA and CONOSRT checklists, which is to include the study design in the title, we only included:
* For PRISMA papers: "systematic search", "systematic review", "systematic literature review", "scoping review", "meta-analyses" or "meta-analysis" in the title (including versions without hyphens)
* For CONSORT papers: "randomised trial", "randomized trial" or "RCT".
The *Scopus* citation data were searched on `r format(date.searched, '%d-%b-%Y')`.
We use a fractional count of citations. So, for example, if a paper had two authors from universities Y and Z, then each university would get a 0.5 weight.
## Summary stats
```{r stats, include=F}
n.res = nrow(papers)
n.papers = length(unique(papers$doi))
```
There were `r n.papers` papers giving a total of `r n.res` author affiliations that could be counted. The average number of affiliations per paper was `r round(10*n.res/n.papers)/10`.
### Missing data
A small number of results were missing the affiliation and/or the country.
These missing results were excluded before calculating the statistics.
##### Missing affiliation
```{r missing.affiliation}
papers$Missing = is.na(papers$affiliation)
tabular(Missing + 1 ~ (Factor(year)+1)*(n=1 + Percent('col')), data=papers)
```
##### Missing country
```{r missing.country}
papers$Missing = is.na(papers$country)
tabular(Missing + 1 ~ (Factor(year)+1)*(n=1 + Percent('col')), data=papers)
```
##### Missing affiliation by country (rows ordered by number missing)
```{r missing.affiliation.by.country}
papers$Missing = is.na(papers$affiliation)
papers$country[is.na(papers$country)] = 'Missing' # need to add missing country for this analysis
tab = with(papers, table(country, Missing))
# calculate percent and order
mtab = as.matrix(tab)
perc = 100* (mtab[,2] / (mtab[,1]+mtab[,2]))
mtab = cbind(mtab, perc)
mtab = mtab[order(-mtab[,2]),] # order by number missing
# sum all rows beyond top ten
top.ten = mtab[1:10, ]
Other = mtab[11:nrow(mtab),]
Other = colSums(Other)
Other[3] = 100* (Other[2] / (Other[1]+Other[2]))
# concatenate
table = rbind(top.ten, Other)
table = rbind(table, colSums(table))
# total
colnames(table) = c('Complete','Missing','Percent missing')
pander(table, style='simple', emphasize.rownames=F, justify=c('right','left','left','left'), digits=0)
# output to latex
ltab = data.frame(table)
ltab = dplyr::mutate(ltab, Country=row.names(ltab),
Percent.missing = round(Percent.missing, 1)) %>%
select(Country, Complete, Missing, Percent.missing)
zz = file('latex.tab.missing.txt','w')
cat(Hmisc::latexTabular(ltab), file=zz)
close(zz)
```
Here we examine whether some countries had more missing affilations than others. This could indicate a disadvantage for some countries.
## Regions by year (excluding missing regions)
The tables show the weighted counts by regions.
It excludes missing regions, but includes data where the region was not missing but the affiliation was missing.
```{r regions}
region.stats <- group_by(papers, year, Region) %>%
filter(is.na(Region)==F) %>% # remove missing
summarise(wsum = sum(weight)) %>% # make weighted count
arrange(year, -wsum) %>%
mutate(Region=as.character(Region), rank = 1:n()) %>%
filter(rank<=10) %>% # top ten
select(-rank) %>%
rename('Year'='year', 'Weighted sum'='wsum') %>%
ungroup()
```
##### 2016
```{r regions.2016}
to.table = dplyr::filter(region.stats, Year==2016) %>%
dplyr::select(-Year)
pander(to.table, style='simple', emphasize.rownames=FALSE, justify=c('left','left'), digits=0)
```
##### 2017
```{r regions.2017}
to.table = dplyr::filter(region.stats, Year==2017) %>%
dplyr::select(-Year)
pander(to.table, style='simple', emphasize.rownames=FALSE, justify=c('left','left'), digits=0)
```
## Top ten countries by year (excluding missing countries)
The tables show the weighted counts by countries.
It excludes data where the country was missing, but includes data where the country was not missing but the affiliation was missing.
```{r countries}
country.stats <- group_by(papers, year, country) %>%
filter(is.na(country)==F) %>% # remove missing
summarise(wsum = sum(weight)) %>% # make weighted count
arrange(year, -wsum) %>%
mutate(rank = 1:n()) %>%
filter(rank<=10) %>% # top ten
select(-rank) %>%
rename('Year'='year', 'Country'='country','Weighted sum'='wsum') %>%
ungroup()
```
##### 2016
```{r countries.2016}
to.table = dplyr::filter(country.stats, Year==2016) %>%
dplyr::select(-Year)
pander(to.table, style='simple', emphasize.rownames=FALSE, justify=c('left','left'), digits=c(0,3))
```
##### 2017
```{r countries.2017}
to.table = dplyr::filter(country.stats, Year==2017) %>%
dplyr::select(-Year)
pander(to.table, style='simple', emphasize.rownames=F, justify=c('left','left'), digits=c(0,3))
```
```{r region.country.latex, include=FALSE}
# don't need regions/countries in second year, because only change was Denmark (2016) and Spain (2017)
# a) regions
null = data.frame(empty=rep('', 10)) # For gaps in latex columns
for.latex = bind_cols(filter(region.stats, Year==2016) %>% select(-Year) %>% mutate(`Weighted sum` = round(`Weighted sum`)),
filter(region.stats, Year==2017) %>% select(-Year, -Region) %>% mutate(`Weighted sum` = round(`Weighted sum`)))
# output to latex
zz = file('latex.tab.region.txt','w')
cat(Hmisc::latexTabular(for.latex), file=zz)
close(zz)
# b) countries
for.latex = bind_cols(filter(country.stats, Year==2016) %>% select(-Year) %>% mutate(`Weighted sum` = round(`Weighted sum`)),
filter(country.stats, Year==2017) %>% select(-Year, -Country) %>% mutate(`Weighted sum` = round(`Weighted sum`)))
# output to latex
zz = file('latex.tab.country.txt','w')
cat(Hmisc::latexTabular(for.latex), file=zz)
close(zz)
```
## Top 50 universities by year (including missing affiliation data)
```{r affiliations, include=FALSE}
papers$affiliation[is.na(papers$affiliation)] = 'Missing' # make missing into a group
# Weighted count per year
istats <- group_by(papers, year, affiliation) %>%
summarise(wsum = sum(weight), n=n()) %>%
arrange(year, -wsum) %>% # sort by year and score
mutate(rank = 1:n() ) %>%
ungroup() %>% # needed for next line
mutate(affiliation = as.character(affiliation))
# add standard rank to istats
load('StandardTable.RData')
standard.table = rename(standard.table, 'standard'='rank', 'year'='Year', 'affiliation'='Affiliation')
istats = left_join(istats, standard.table, by=c('affiliation','year')) %>%
filter(is.na(rank)==FALSE) # remove all results not in istats
```
##### 2016
```{r affiliations.2016}
to.table = filter(istats, year==2016) %>%
filter(rank <= 50) %>% # top fifty
mutate(standard = round(standard)) %>% # round the standard rank
select(rank, affiliation, n, wsum, standard)
pander(to.table, style='simple', emphasize.rownames=F, justify=c('right','left','left','left','left'), digits=c(0,0,0,3,0))
# output to latex
for.latex = to.table[1:50,]
for.latex$wsum = round(for.latex$wsum*10)/10
zz = file('latex.tab.top.50.2016.txt','w')
cat(Hmisc::latexTabular(for.latex), file=zz)
close(zz)
```
##### 2017
```{r affiliations.2017}
to.table = filter(istats, year==2017) %>%
filter(rank <= 50) %>% # top fifty
mutate(standard = round(standard)) %>% # round the standard rank
select(rank, affiliation, n, wsum, standard)
pander(to.table, style='simple', emphasize.rownames=F, justify=c('right','left','left','left','left'), digits=c(0,0,0,3,0))
# output to latex
for.latex = to.table[1:50,]
for.latex$wsum = round(for.latex$wsum*10)/10
zz = file('latex.tab.top.50.2017.txt','w')
cat(Hmisc::latexTabular(for.latex), file=zz)
close(zz)
```
### Correlation of good practice and standard ranks
This is restricted to universities with a standard rank below 2000.
```{r standard.corr}
to.corr = filter(istats, standard<2000)
c = with(to.corr, cor(rank, standard, use = 'complete.obs', method='spearman'))
cplot = ggplot(data=to.corr, aes(x=rank, y=standard, col=factor(year)))+
geom_point()+
xlab('Good research practice rank')+
ylab('Standard rank')+
scale_color_manual('Year', values=cbbPalette[2:3])+
theme_bw()
cplot
```
The Spearman's correlation is `r roundz(c,2)`.
##### Bland-Altman plot of the university rank
The plot looks at institution ranking only for those in the top 200.
```{r BA.rank.uni.stats, include=FALSE}
bstats = group_by(istats, year) %>%
mutate(rank = 1:n()) %>%
filter(rank <=200) # top 200 only
stats2016 = subset(bstats, year==2016)
stats2017 = subset(bstats, year==2017)
wide = merge(stats2016, stats2017, by='affiliation')
bstats = bland.altman.plot(rank(-wide$wsum.x), rank(-wide$wsum.y), main="", xlab='', ylab="", silent=F, graph.sys = 'base') # just get the stats
# quick check of calculations
wide = mutate(wide, rank.x = rank(-wide$wsum.x),
rank.y = rank(-wide$wsum.y),
diff = rank.x - rank.y,
mean = (rank.x + rank.y)/2)
```
```{r BA.rank.uni.plot}
bplot.uni = bland.altman.plot(rank(-wide$wsum.x), rank(-wide$wsum.y), main="", xlab='', ylab="", silent=T, graph.sys = 'ggplot2')
bplot.uni = bplot.uni + theme_bw() + theme(plot.margin = margin(1, 1, 1, 1, "mm")) +
xlab("Mean rank") +
ylab('Difference in rank')
bplot.uni
```
There were `r nrow(wide)` universities in the top 200 in both years.
The plot includes the limits of agreement which are `r round(bstats$lines[1])` to `r round(bstats$lines[3])`.
##### Examine those insitutions with a very large change (over 90)
```{r large.change}
lchange = mutate(wide, diff = rank.x - rank.y) %>%
filter(diff > 90 | diff < -90) %>%
select(-year.x, -year.y)
pander(lchange, style='simple', digits=0)
```
The table shows those institutions that had a change in rank of over 90.
The first three columns are for 2016 and the next three for 2017.
##### List the papers from insitutions with a very large change
```{r large.change.list}
if(length(dir(pattern='Affiliation.check.results.RData')) == 0){
tlist = filter(papers, affiliation %in% lchange$affiliation)
# quick check of change in weight
#group_by(tlist, affiliation, year) %>%
# summarise(mean(weight), sd(weight), sum(weight>0.5))
adetails = NULL
for (k in 1:nrow(tlist)){
doi = paste(tlist$doi[k], '[DOI]', sep='')
search.res = entrez_search(db='pubmed', term=doi)
if(length(search.res$ids)==0){
frame = data.frame(affiliation=tlist$affiliation[k], year=tlist$year[k], authors='', title='', journal='')
}
if(length(search.res$ids)>0){
details = parse_pubmed_xml(entrez_fetch(db="pubmed", id=search.res$ids, rettype="xml"))
frame = data.frame(affiliation=tlist$affiliation[k], year=tlist$year[k], authors=paste(details$authors, collapse=';'), title=details$title, journal=details$journal)
}
adetails = rbind(adetails, frame)
}
adetails = arrange(adetails, affiliation, year) %>%
distinct()
# store
save(adetails, file='Affiliation.check.results.RData')
}
if(length(dir(pattern='Affiliation.check.results.RData')) > 0){
load('Affiliation.check.results.RData')
}
# output to latex
zz = file('check.odd.txt','w')
for.table = dplyr::filter(adetails, affiliation =='University of Liverpool')
cat(Hmisc::latexTabular(for.table), file=zz)
close(zz)
```
### Score distributions for universities
```{r score.dist}
dplot = ggplot(data=istats, aes(x=wsum))+
geom_histogram(fill='skyblue')+
theme_bw()+
ylab('Frequency')+
xlab('Score')+
facet_wrap(~year, ncol=1)
dplot
postscript('Distributions.eps', width=6, height=5, horiz=F)
print(dplot)
invisible(dev.off())
```
These histrograms use `r format(nrow(istats),big.mark=',')` scores across 2016 and 2017.
##### Boxplot of scores by year
The y-axis is on a log base-2 scale.
```{r score.box}
# log base 2
breaks = c(0.1, 1, 10, 40, 100)
lbreaks = log2(breaks)
bplot = ggplot(data=istats, aes(x=factor(year), y=log2(wsum)))+
geom_boxplot(fill='skyblue')+
theme_bw()+
scale_y_continuous(breaks=lbreaks, labels=breaks)+
xlab('Year')+
ylab('Score')+
theme(panel.grid.minor = element_blank())
bplot
postscript('Boxplots.eps', width=6, height=5, horiz=F)
print(bplot)
invisible(dev.off())
```
These boxplots use `r format(nrow(istats),big.mark=',')` scores across 2016 and 2017.
## Times Higher Education
Here we examine the Times Higher Education (THE) data for 2016 and 2017.
The league table is called the "THE World University Rankings".
##### Bland-Altman plot of the institute rank for THE World University Rankings data
The plot looks at institution ranking only for those in the top 200.
A higher rank indicates higher prestige.
There is a clear "funnel" to the plot, with less movement at higher ranks.
```{r BA.rank.THE, include=FALSE}
THE.stats = group_by(THE, year) %>%
mutate(rank.num = rank(-research)) %>% # use research score
filter(rank.num <= 200) # top 200
wide = dcast(inst ~ year, value.var='rank.num', data=THE.stats)
wide = wide[complete.cases(wide), ] # remove missing
bstats = bland.altman.plot(wide$`2016`, wide$`2017`, main="", xlab='', ylab="", silent=F, graph.sys = 'base') # just get the stats
```
```{r BA.rank.THE.plot}
bplot.THE = bland.altman.plot(wide$`2016`, wide$`2017`, main="", xlab='', ylab="", silent=T, graph.sys = 'ggplot2')
bplot.THE = bplot.THE + theme_bw() + theme(plot.margin = margin(1, 1, 1, 1, "mm")) +
xlab("Mean rank") +
ylab('Difference in rank')
bplot.THE
```
There were `r nrow(wide)` universities in the top 200 in both years.
The plot includes the limits of agreement which are `r round(bstats$lines[1])` to `r round(bstats$lines[3])`.
```{r BA.plot.both, include=FALSE}
# Add THE and EQUATOR Bland-Altman plots to one graph
bplot.uni = bplot.uni + ggtitle('Good Research Practice rankings') + scale_x_continuous(limits=c(0,200)) + scale_y_continuous(limits=c(-110,110)) # consistent scales
bplot.THE = bplot.THE + ggtitle('THE World University rankings') + scale_x_continuous(limits=c(0,200)) + scale_y_continuous(limits=c(-110,110)) + ylab('') # consistent scales
postscript('BAplots.eps', width=7.5, height=5, horiz=F)
grid.arrange(bplot.uni, bplot.THE, ncol=2)
invisible(dev.off())
```
## Bootstrap to get uncertainty in university ranks
Includes 'missing' affiliation as a category.
The results are sorted according to the probability of being in the top 10.
```{r boostrap}
n.boot = 1000 # number of bootstrap replications (should be 1000)
set.seed(12345)
if(length(dir(pattern='Boostrap.results.RData')) == 0){ # only run if results file does not already exist
### 2016
to.boot = dplyr::select(papers, affiliation, weight, year) # reduce number of columns
to.boot = subset(to.boot, year==2016)
bstats = NULL
for (k in 1:n.boot){
b = sample(1:nrow(to.boot), size=nrow(to.boot), replace=T)
boot = to.boot[b, ]
boot_by_year <- group_by(boot, year, affiliation)
# make weighted count by year
boot.stats = summarise(boot_by_year, wsum = sum(weight)) %>%
arrange(year, -wsum)
boot.stats$rank = 1:nrow(boot.stats) #
bstats = rbind(bstats, boot.stats)
}
bstats <- group_by(bstats, affiliation)
bstats$top10 = bstats$rank <= 10 # pr top 10 and top 100
bstats$top100 = bstats$rank <= 100
intervals.2016 = summarise(bstats,
p10 = mean(top10), p100 = mean(top100),
slower=quantile(wsum, 0.025), supper=quantile(wsum, 0.975),
rmedian=quantile(rank, 0.5), rlower=quantile(rank, 0.025), rupper=quantile(rank, 0.975)) %>%
arrange(rmedian, -p10)
stats2016.top20 = intervals.2016[1:20, c('affiliation','p10','rmedian','rlower','rupper')] # top 20
names(stats2016.top20) = c('Affiliation', 'Pr top 10', 'Median rank', 'Lower rank', 'Upper rank')
### 2017 (repeat, bad coding by me)
to.boot = dplyr::select(papers, affiliation, weight, year) # reduce number of columns
to.boot = subset(to.boot, year==2017)
bstats = NULL
for (k in 1:n.boot){
b = sample(1:nrow(to.boot), size=nrow(to.boot), replace=T)
boot = to.boot[b, ]
boot_by_year <- group_by(boot, year, affiliation)
# make weighted count by year
boot.stats = summarise(boot_by_year, wsum = sum(weight)) %>%
arrange(year, -wsum)
boot.stats$rank = 1:nrow(boot.stats) #
bstats = rbind(bstats, boot.stats)
}
bstats <- group_by(bstats, affiliation)
bstats$top10 = bstats$rank <= 10 # pr top 10 and top 100
bstats$top100 = bstats$rank <= 100
intervals.2017 = summarise(bstats,
p10 = mean(top10), p100 = mean(top100),
slower=quantile(wsum, 0.025), supper=quantile(wsum, 0.975),
rmedian=quantile(rank, 0.5), rlower=quantile(rank, 0.025), rupper=quantile(rank, 0.975)) %>%
arrange(rmedian, -p10)
stats2017.top20 = intervals.2017[1:20, c('affiliation','p10','rmedian','rlower','rupper')] # top 20
names(stats2017.top20) = c('Affiliation', 'Pr top 10', 'Median rank', 'Lower rank', 'Upper rank')
# save
save(stats2016.top20, stats2017.top20, intervals.2016, intervals.2017, file='Boostrap.results.RData')
}
if(length(dir(pattern='Boostrap.results.RData')) > 0){
load('Boostrap.results.RData') # load existing results
}
intervals = dplyr::bind_rows(intervals.2016, intervals.2017) # used later
pander(stats2016.top20, style='simple', emphasize.rownames=F, justify=c('right','left','left','left','left'), digits=c(0,2,0,0,0))
```
#### Plot of uncertainty in rank by median rank for 2017
```{r uncertainty}
intervals.2017 = dplyr::mutate(intervals.2017, rank.diff = rupper - rlower)
pplot = ggplot(data=intervals.2017, aes(x=rmedian, y=rank.diff))+
geom_point()+
xlab('Median rank')+
ylab('Range in ranks')+
theme_bw()
pplot
```
#### Plot of interval width against median rank
The plot is just for the top 200 and shows both years.
```{r plot.smooth.uncertainty}
to.plot = dplyr::filter(intervals, rmedian<=200) %>%
mutate(rank.diff = rupper - rlower)
lplot = ggplot(data=to.plot, aes(x=rmedian, y=rank.diff))+
geom_point()+
geom_smooth(method='lm',formula=y~x, col='dark red', se=FALSE)+
xlab('Rank')+
ylab('Interval width')+
theme_bw()+
theme(text=element_text(size=16))
lplot
postscript('BootWidth.eps', width=6, height=5, horiz=F)
print(lplot)
invisible(dev.off())
# linear regression
lmodel = lm(rank.diff ~ I(rmedian/10), data=to.plot)
ci = confint(lmodel)
inc = round(lmodel$coefficients[2]*10)/10
inc.l = round(ci[2,1]*10)/10
inc.u = round(ci[2,2]*10)/10
```
For every 10 unit increase in rank the width of the interval increases by an average of `r inc` (95% CI `r inc.l` to `r inc.u`).
# Bayesian mixture model to estimate clusters
```{r bayes.cluster}
# only run if not already saved
if(length(dir(pattern='bugs.cluster.results.RData')) == 0){ # only run if results file does not already exist
bugsfile = 'cluster.bugs.txt'
bugs = file(bugsfile, 'w')
cat('model{
for (i in 1:N){
wsum[i] ~ dnorm(mu[i], tau)
mu[i] <- cluster[class[i]] # mean dependent on class membership
class[i] ~ dcat(P[1:N.clust]) # class membership
}
# minimum cluster size
for (k in 1:N.clust){
P.dash[k] ~ dunif(1, 24.75) # upper limit is 99/4
P[k] <- P.dash[k] / P.total
}
P.total <- sum(P.dash[1:N.clust])
# ordered values for mean
c[1] ~ dexp(1)
cluster[1] <- 2 + c[1] # because of two minimum
for (k in 2:N.clust){
c[k] ~ dexp(1)
cluster[k] <- c[k] + cluster[k-1] # always increase
}
tau ~ dgamma(1, 1)
}\n', file=bugs)
close(bugs)
# Just above 2
for.cluster = dplyr::filter(istats, wsum > 2)
# Pre-specify cluster size of 5
N.clust = 5
bdata = list(N=nrow(for.cluster), N.clust=N.clust, wsum=for.cluster$wsum) #
inits = list(list(tau=0.1, c=rep(1,5), P.dash=rep(1, 5), class=rep(1, nrow(for.cluster))))
parms = c('cluster','class','P','tau')
bugs.results.detail = bugs(data=bdata, inits=inits, parameters=parms, model.file=bugsfile,
n.chains=1, n.thin=5, n.burnin
=10000, n.iter=20000, debug=TRUE, DIC=FALSE,
bugs.directory="c:/Program Files/WinBUGS14")
# save
for.cluster$cluster.member = round(as.numeric(bugs.results.detail$median$class)) # median group
save(bugs.results.detail, for.cluster, file='bugs.cluster.results.RData')
}
if(length(dir(pattern='bugs.cluster.results.RData')) > 0){
load('bugs.cluster.results.RData') # load existing results
}
# numbers for text below.
above = sum(istats$wsum >= 2)
percent.above = round(100 * above / nrow(istats))
```
Here we only examine universities that had a score of two or more, which was `r above` universities, `r percent.above`% of the total sample.
The model includes "missing" as a university.
We pre-specify the number of clusters as five, and do not try to find a more statistically optimal number as both authors agreed on this number of groups before any modelling.
We used a burn-in of 10,000 followed by a sample of 10,000 thinned by 5 to give a sample of 2,000 estimates.
### Cluster means and 95% credible intervals (alternative clustering)
```{r plot.cluster.means}
cluster.means = bugs.results.detail$summary[grep('cluster', row.names(bugs.results.detail$summary)), c(1,3,7)]
cluster.means = data.frame(cluster.means) %>%
rename('lower'="X2.5.", 'upper'="X97.5.") %>%
mutate(cluster = 1:n())
mplot = ggplot(data=cluster.means, aes(x=mean, xmin=lower, xmax=upper, y=cluster))+
geom_point(size=2)+
geom_errorbarh(height=0, size=1.1)+
theme_bw()+
ylab('Cluster')+
xlab('Score')+
theme(panel.grid.minor = element_blank())
mplot
```
### Table of probabilities and cluster means
```{r cluster.table}
P.means = bugs.results.detail$summary[grep('P', row.names(bugs.results.detail$summary)), c(1,3,7)]
P.means = data.frame(P.means) %>%
rename('lower'="X2.5.", 'upper'="X97.5.") %>%
mutate(cluster = 1:n())
for.table = inner_join(P.means, cluster.means, by='cluster') %>%
mutate(P=round(100*mean.x)/100, score=round(mean.y, 1), CI=paste(round(lower.y, 1), ' to ', round(upper.y, 1), sep='')) %>%
select(cluster, P, score, CI)
pander(for.table, style='simple')
# latex
zz = file('latex.tab.P.cluster.txt','w')
cat(Hmisc::latexTabular(for.table), file=zz)
close(zz)
```
#### Examine uncertainty in group membership
In the plot below we examine the difference from the modal cluster for each university.
A score of zero indicates perfect membership.
```{r cluster.uncertainty}
mat = as.matrix(bugs.results.detail$sims.array[,1,]) # chains
index = grep('class', colnames(mat))
mat = mat[, index]
uncertain = NULL
for (i in 1:ncol(mat)){
tab = table(mat[,i]) # table of frequencies
stat = (nrow(mat) - max(tab)) / nrow(mat) # disagreement from mode
mode = names(tab[which(tab==max(tab))])
frame = data.frame(mode = mode, entropy=stat)
uncertain = rbind(uncertain, frame)
}
uncertain$mode = as.numeric(as.character(uncertain$mode))
uplot = ggplot(data=uncertain, aes(x=factor(mode), y=entropy))+
geom_boxplot()+
theme_bw()+
xlab('Modal cluster')+
ylab('Difference from mode')
uplot
```
Groups 1 and 2 are very uncertain and also have a similar mean. These two groups could probably be combined to give a cluster size of four.
#### Cross-tabulation of changes in cluster membership (only those in both years)
```{r cluster.membership}
# look for change in group
wide = dcast(affiliation ~ year, data=for.cluster, value.var='cluster.member')
wide$y2016 = factor(wide$`2016`)
wide$y2017 = factor(wide$`2017`)
# remove missing (only in both years)
wide = filter(wide, is.na(y2016)==FALSE & is.na(y2017)==FALSE)
# now table
table = tabular(y2016 + 1~ (y2017+1) * (n=1), data=wide) # excludes missing
pander(table)
# for stats below
tab = with(wide, table(y2016, y2017))
no.change = sum(diag(tab))
N = sum(tab)
# output to latex
zz = file('latex.tab.cluster.txt','w')
cat(Hmisc::latexTabular(table), file=zz)
close(zz)
```
The number of universities that did not change cluster between 2016 and 2017 was `r no.change` (`r round(100*no.change/N, 0)`%).
##### Universities that went from a '4' to a '5'
```{r list.fallers}
list = dplyr::filter(wide, `2016`=='4' & `2017` == '5') %>%
select('affiliation')
pander(list, style='simple')
```
##### Universities that went from a '3' to a '4'
```{r list.risers}
list = dplyr::filter(wide, `2016`=='3' & `2017` == '4') %>%
select('affiliation')
pander(list, style='simple')
```
```{r latex, include=FALSE}
## top ten table output to latex
# merge scores, clusters and bootstrap
# 2016
table.2016 = inner_join(stats2016.top20[1:10,], stats2016, by=c('Affiliation'='affiliation')) %>% mutate(year=2016) # bootstrap and mean
wide.2016 = dplyr::select(wide, affiliation, `2016`) %>% rename('cluster' = `2016`) # cluster
table.2016 = inner_join(table.2016, wide.2016, by=c('Affiliation'='affiliation'))
# 2017
table.2017 = inner_join(stats2017.top20[1:10,], stats2017, by=c('Affiliation'='affiliation')) %>% mutate(year=2017)
wide.2017 = dplyr::select(wide, affiliation, `2017`) %>% rename('cluster' = `2017`)
table.2017 = inner_join(table.2017, wide.2017, by=c('Affiliation'='affiliation'))
make.table = rbind(table.2016, table.2017)
#
make.table = mutate(make.table,
`Pr top 10` = round(`Pr top 10`, 2),
wsum = round(wsum, 1),
standard = round(standard),
range=paste(`Median rank`, ' (', `Lower rank`, ' to ', `Upper rank`, ')', sep='')) %>%
arrange(year, -wsum) %>%
select(year, Affiliation, n, wsum, cluster, range, standard) # dropped `Pr top 10`
# output to latex
zz = file('latex.tab.top10.txt','w')
cat(Hmisc::latexTabular(make.table), file=zz)
close(zz)
```
### Alternative clustering #1
Here we use the same model as above, but include the sample size.
This led to too few clusters, but with more membership certainty.
```{r bayes.cluster.alternative}
# Bayesian clustering model to give league table groups rather than ranks
# Gaussian mixture model
# use istats data from `affiliations` chunk
# use both years, allows us to examine change; ignore within-university correlation
# tried changing sigma2 to sigma2[class[i]]; results were not as useful
# version including sample size
# only run if not already saved
if(length(dir(pattern='bugs.cluster.results.alternative.RData')) == 0){ # only run if results file does not already exist
bugsfile = 'cluster.bugs.alternative.txt'
bugs = file(bugsfile, 'w')
cat('model{
for (i in 1:N){
wsum[i] ~ dnorm(mu[i], tau[i])
tau[i] <- n[i]/sigma2 #
mu[i] <- cluster[class[i]] # mean dependent on class membership
class[i] ~ dcat(P[1:N.clust]) # class membership
}
# minimum cluster size
for (k in 1:N.clust){
P.dash[k] ~ dunif(1, 24.75) # upper limit is 99/4
P[k] <- P.dash[k] / P.total
}
P.total <- sum(P.dash[1:N.clust])
# ordered values for mean
c[1] ~ dexp(1)
cluster[1] <- 2 + c[1] # because of two minimum
for (k in 2:N.clust){
c[k] ~ dexp(1)
cluster[k] <- c[k] + cluster[k-1] # always increase
}
sigma2 ~ dunif(0.01, 1000)
}\n', file=bugs)
close(bugs)
# Just 2 or above
for.cluster = dplyr::filter(istats, wsum >= 2)
# Pre-specify cluster size of 5
N.clust = 5
bdata = list(N=nrow(for.cluster), N.clust=N.clust, wsum=for.cluster$wsum, n=for.cluster$n) #
inits = list(list(sigma2=1, c=rep(1,5), P.dash=rep(1, 5), class=rep(1, nrow(for.cluster))))
parms = c('cluster','class','P','sigma2')
bugs.results.detail = bugs(data=bdata, inits=inits, parameters=parms, model.file=bugsfile,
n.chains=1, n.thin=5, n.iter=20000, debug=FALSE, DIC=FALSE,
bugs.directory="c:/Program Files/WinBUGS14")
# save
for.cluster$cluster.member = as.numeric(bugs.results.detail$median$class) # median group
save(bugs.results.detail, for.cluster, file='bugs.cluster.results.alternative.RData')
}
if(length(dir(pattern='bugs.cluster.results.alternative.RData')) > 0){
load('bugs.cluster.results.alternative.RData') # load existing results
}
```
### Cluster means and 95% credible intervals
```{r plot.cluster.means.alternative}
cluster.means = bugs.results.detail$summary[grep('cluster', row.names(bugs.results.detail$summary)), c(1,3,7)]
cluster.means = data.frame(cluster.means) %>%
rename('lower'="X2.5.", 'upper'="X97.5.") %>%
mutate(cluster = 1:n())
mplot = ggplot(data=cluster.means, aes(x=mean, xmin=lower, xmax=upper, y=cluster))+
geom_point(size=2)+
geom_errorbarh(height=0, size=1.1)+
theme_bw()+
ylab('Cluster')+
xlab('Score')+
theme(panel.grid.minor = element_blank())
mplot
```
The 95% credible intervals for the means are relatively narrow.
### Table of probabilities and cluster means
```{r cluster.table.alternative}
P.means = bugs.results.detail$summary[grep('P', row.names(bugs.results.detail$summary)), c(1,3,7)]
P.means = data.frame(P.means) %>%
rename('lower'="X2.5.", 'upper'="X97.5.") %>%
mutate(cluster = 1:n())
for.table = inner_join(P.means, cluster.means, by='cluster') %>%
mutate(P=round(100*mean.x)/100, score=round(mean.y, 1), CI=paste(round(lower.y, 1), ' to ', round(upper.y, 1), sep='')) %>%
select(cluster, P, score, CI)
pander(for.table, style='simple')
# latex
zz = file('latex.tab.P.cluster.alternative.txt','w')
cat(Hmisc::latexTabular(for.table), file=zz)
close(zz)
```
The columns are the percent probabilities ($\pi$) and cluster means ($\overline{x}$) and confidence intervals.
#### Examine uncertainty in group membership
In the plot below we examine the difference from the modal cluster for each university.
A score of zero indicates no uncertainty in membership.
```{r cluster.uncertainty.alternative}
mat = as.matrix(bugs.results.detail$sims.array[,1,]) # chains
index = grep('class', colnames(mat))
mat = mat[, index]
uncertain = NULL
for (i in 1:ncol(mat)){
tab = table(mat[,i]) # table of frequencies
stat = (nrow(mat) - max(tab)) / nrow(mat) # disagreement from mode
mode = names(tab[which(tab==max(tab))])
frame = data.frame(mode = mode, entropy=stat)
uncertain = rbind(uncertain, frame)
}
uncertain$mode = as.numeric(as.character(uncertain$mode))
uplot = ggplot(data=uncertain, aes(x=factor(mode), y=entropy))+
geom_boxplot()+
theme_bw()+
xlab('Modal cluster')+
ylab('Difference from mode')
uplot
```
#### Cross-tabulation of changes in cluster membership (only those in both years)
```{r cluster.membership.alternative.with.sample.size}
# look for change in group
wide = dcast(affiliation ~ year, data=for.cluster, value.var='cluster.member')
wide$y2016 = factor(wide$`2016`)
wide$y2017 = factor(wide$`2017`)
table = tabular(y2016 + 1~ (y2017+1) * (n=1), data=wide) # excludes missing
pander(table)
# for stats below
tab = with(wide, table(y2016, y2017))
no.change = sum(diag(tab))
N = sum(tab)
# output to latex
zz = file('latex.tab.cluster.alternative.txt','w')
cat(Hmisc::latexTabular(table), file=zz)
close(zz)
```
The number of universities that did not change cluster between 2016 and 2017 was `r no.change` (`r round(100*no.change/N, 0)`%).
### Alternative clustering #2
Here we use the alternative clustering assuming a Gaussian mixture model fitted using a non-Bayesian EM algorithm. This clustering does not account for the sample size.
```{r alt.cluster}
fit = Mclust(data=for.cluster$wsum, G=1:5, modelNames="V", verbose=FALSE)
summary(fit)
# density plot
plot(fit, what="density", main="", xlab="Score")
rug(for.cluster$wsum)
```
```{r include=FALSE}
## prepare processed data for shiny
load("bugs.cluster.results.RData") # re-load bayesian cluster data
# a) merge Bayesian cluster model with bootstrap data
intervals.2016$year = 2016
intervals.2017$year = 2017
intervals = dplyr::bind_rows(intervals.2016, intervals.2017)
results = left_join(for.cluster, intervals, by=c('year','affiliation')) # only where there's cluster data, so score of 2+
# b) merge in region and country information
country = select(papers, country, Region, affiliation) %>%
unique()
# remove some weird doubles
w.doubles = c('Ludwig-Maximilians-Universität München','Universitat Autònoma de Barcelona','Universität Heidelberg','Université Catholique de Louvain')
for (w in w.doubles){
odd = grep(w, country$affiliation)
if(length(odd)>1){
index = 1:nrow(country)
index = index[index!=odd[1]] # remove one
country = country[index,]
}
}
# if missing affiliation then set country and region to missing (else merge is messed up)
index = country$affiliation == 'Missing'
country$country[index] = 'Missing'
country$Region[index] = 'Missing'
country = unique(country) # now remove doubled-up missing rows
results = left_join(results, country, by=c('affiliation')) %>%
select(year, country, Region, affiliation, wsum, n, rank, cluster.member, p10, rlower, rupper) %>%
unique() # remove few odd duplicates
save(results, file = 'Processed.papers.for.Shiny.RData')
```
# Comparison with standard table
Here we examine how the universities in our table performed in a standard league table using publication counts.
We searched for total publication counts by year in _Scopus_ and only included articles (not books, book chapters, editorial or letters). To match our good practice table, we only included papers in the three subject areas of Dentistry, Health Professions and Nursing.
#### Top 10 universities in 2016 in standard table
```{r standard.top.10}
load('StandardTable.RData') # from standard_table.scopus.R