Ogive (cumulative relative frequency graph)

An ogive plots running totals instead of the count inside each bin, so it answers questions of the form how much of the data sits at or below this value. For example, with 40 test scores, if 30 of them are 80 or lower the graph passes through the point $(80, 0.75)$, since $30 / 40 = 0.75$. The curve never goes down and finishes at $1$, that is, 100 percent, which makes it a direct way to read percentiles off a graph. The AP Statistics course framework does not name ogives, so you will meet them more often in college courses and older textbooks.