<<results=tex>>=
    get_changes <- function(project, sign_num){
        summary<-fivenum(abs(project$improvement[sign(project$improvement)==sign_num]))
        summary[c(1,3,5)]
    }
    improvements <- sapply(list(argouml, jabref, jedit, mucommander), get_changes, 1)
    decreases <- sapply(list(argouml, jabref, jedit, mucommander), get_changes, -1)
    changes <- rbind(improvements, decreases)
    colnames(changes)<-rownames(projects)
    rownames(changes)<-c('Minimum (+)', 'Median (+)', 'Maximum (+)', 'Minimum (-)', 'Median (-)', 'Maximum (-)')
    format_table(c(hlines(4)), xtable(changes, caption='Changes in position for improved (+) and worsened (-) bugs (\\combined)', label='tab:improvements', digits=0), table.placement='t') 
@
