6.2.4
Cumulative Frequency 2
Cumulative Frequency Analysis
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.


Estimation not calculation
Estimation not calculation
- Cumulative frequency diagrams can be used to estimate values.
- Cumulative frequency diagrams CANNOT be used to work out accurate values.


The median piece of data
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.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Median from cumulative frequency
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 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.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Quartiles
Quartiles
- A set of data can be split into four quartiles.
- Each quartile includes of the pieces of data in the data set.
- The values , and of the way through a set of data are known as Q1, Q2 and Q3 respectively.
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Calculating the quartiles
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).
,h_400,q_80,w_640.png)
,h_400,q_80,w_640.png)
Interquartile range
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.
1Numbers
1.1Integers
1.3Decimals
1.4Powers & Roots
1.5Set Language & Notation
1.6Percentages
1.7Ratio & Proportion
2Equations, Formulae & Identities
2.1Algebraic Manipulation
2.2Expressions & Formulae
2.3Linear Equations
2.4Quadratic Equations
2.5Proportion
3Sequences, Functions & Graphs
3.1Sequences
3.3Graphs
3.4Common Graphs
4Geometry
4.1Angles, Lines & Triangles
4.2Polygons
4.5Circle Properties
4.6Trigonometry & Pythagoras’ theorem
4.7Mensuration of 2D Shapes
4.83D Shapes & Volume
5Vectors & Transformation Geometry
6Statistics & Probability
6.1Statistical Measures
6.2Graphical Representation of Data
Jump to other topics
1Numbers
1.1Integers
1.3Decimals
1.4Powers & Roots
1.5Set Language & Notation
1.6Percentages
1.7Ratio & Proportion
2Equations, Formulae & Identities
2.1Algebraic Manipulation
2.2Expressions & Formulae
2.3Linear Equations
2.4Quadratic Equations
2.5Proportion
3Sequences, Functions & Graphs
3.1Sequences
3.3Graphs
3.4Common Graphs
4Geometry
4.1Angles, Lines & Triangles
4.2Polygons
4.5Circle Properties
4.6Trigonometry & Pythagoras’ theorem
4.7Mensuration of 2D Shapes
4.83D Shapes & Volume
5Vectors & Transformation Geometry
6Statistics & Probability
6.1Statistical Measures
6.2Graphical Representation of Data
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