table(d$num.calls, d$absences)
 
-ggplot(data=d) +
-    aes(x=as.factor(num.calls), y=absences) +
-    geom_violin()
-
 ## png("questions_absence_histogram_combined.png", units="px", width=600, height=400)
 
 ggplot(d) +
     aes(x=as.factor(num.calls), fill=as.factor(absences)) +
     geom_bar(color="black") +
     stat_count() +
-    scale_x_discrete("Number of questions asked") +
+    scale_x_discrete("Number of questions answered") +
     scale_y_continuous("Number of students") +
     ##scale_fill_brewer("Absences", palette="Blues") +
     scale_fill_manual("Absences", values=color.gradient) +
     aes(x=as.factor(num.calls)) +
     geom_bar() +
     stat_count() +
-    scale_x_discrete("Number of questions asked as of 2020-02-12") +
+    scale_x_discrete("Number of questions answered") +
     scale_y_continuous("Number of students") +
     theme_bw() +
     facet_wrap(.~absences, ncol=5, labeller="absence.labeller")