gistfile1.txt

histogram(~ SurvTimeWeek | is.na(Physical_Functioning), data = total)  
histogram(~ Emotional_Functioning | is.na(Physical_Functioning), data = total)  
histogram(~ SurvTimeWeek | timef*is.na(Interference), data = total,type = "density",
          panel = function(x, ...) {
            panel.histogram(x, ...)
            panel.mathdensity(dmath = dnorm, col = "black",
                              args = list(mean=mean(x),sd=sd(x)))
          } )
histogram(~ Severity | timef*is.na(Relief), data = total) 
histogram(~ Severity | timef*is.na(Pain), data = total)