Ogive

Definition

An ogive (cumulative frequency curve) plots the running total of frequencies against the upper class boundaries of grouped data. You use it to estimate the median, quartiles and percentiles, and how many values lie below a given value.

Worked example

With 80 values, read the median at a cumulative frequency of 40, Q1 at 20 and Q3 at 60.

To find how many learners scored less than 50%, read up from 50 on the horizontal axis to the curve, then across to the cumulative frequency.

Where it appears in the exam

Ogive is part of the statistics section of CAPS Grade 11 Mathematics and is examined in Paper 2 of the November exam.

Step-by-step method

1. Make a cumulative frequency column.
2. Plot each cumulative frequency at its class's upper boundary.
3. Start at the lower boundary of the first class with a frequency of 0.
4. Join the points with a smooth curve.

Common mistake

Plotting cumulative frequencies at the class midpoints instead of the upper boundaries.

Related statistics terms

• Standard deviation
• Least squares regression line
• Correlation coefficient
• Outlier
• Interquartile range
• Five-number summary

Frequently asked questions

What does ogive mean in Grade 11 Maths?

An ogive (cumulative frequency curve) plots the running total of frequencies against the upper class boundaries of grouped data. You use it to estimate the median, quartiles and percentiles, and how many values lie below a given value.

Which paper tests ogive in Grade 11?

Ogive belongs to the Statistics section of CAPS Grade 11 Mathematics, which is examined in Paper 2 of the November exam.

How do I practise questions involving ogive?

Snap a question that uses ogive into Snap&Learn with your grade set to Grade 11, or work through the Grade 11 topic guide and practice papers.