6.2.4

Cumulative Frequency 2

Test yourself

Cumulative Frequency Analysis

Cumulative frequency diagrams can be used to estimate different important values in a set of data such as the median, quartiles and inter-quartile range.

Illustrative background for Estimation not calculationIllustrative background for Estimation not calculation ?? "content

Estimation not calculation

  • Cumulative frequency diagrams can be used to estimate values.
  • Cumulative frequency diagrams CANNOT be used to work out accurate values.
Illustrative background for The median piece of dataIllustrative background for The median piece of data ?? "content

The median piece of data

  • You can find which person is the middle piece of data using the equation above.
  • You can then use this to find the value of the median piece of data.
Illustrative background for Median from cumulative frequencyIllustrative background for Median from cumulative frequency ?? "content

Median from cumulative frequency

  • The median of a set of data can be estimated by drawing a line from the middle piece of data on your cumulative frequency diagram on the y-axis until it hits the curve.
  • Then draw a vertical line down to the x-axis.
  • The number on the x-axis is an estimate for the median.

Cumulative Frequency Analysis

Cumulative frequency diagrams can be used to estimate different important values in a set of data such as the median, quartiles and inter-quartile range.

Illustrative background for QuartilesIllustrative background for Quartiles ?? "content

Quartiles

  • A set of data can be split into four quartiles.
  • Each quartile includes 14\large\frac{1}{4} of the pieces of data in the data set.
  • The values 14\large\frac{1}{4}, 24\large\frac{2}{4} and 34\large\frac{3}{4} of the way through a set of data are known as Q1, Q2 and Q3 respectively.
Illustrative background for Calculating the quartilesIllustrative background for Calculating the quartiles ?? "content

Calculating the quartiles

  • Quartiles can be calculated in a similar way to the median.
    • Start by finding the median value (this is the same as Q2).
    • Then find the median of the bottom half of the data smaller than Q2 (this is Q1).
    • Then find the median of the top half of the data larger than Q2 (this is Q3).
Illustrative background for Interquartile rangeIllustrative background for Interquartile range ?? "content

Interquartile range

  • The interquartile range is a measure of how spread out the data is.
  • You calculate the interquartile range by working out Q3 − Q1.

Jump to other topics

1Numbers

2Equations, Formulae & Identities

3Sequences, Functions & Graphs

4Geometry

5Vectors & Transformation Geometry

6Statistics & Probability

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium