# Box plots, Stem and Leaf, Frequency Diagrams, Line Graphs, Frequency Trees and Venn Diagrams

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## Quick Note

Hi quick note, I honestly have no idea what topic these are so if someone could comment that'd be great! Thanks for using my cards! :)

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## Box Plots

To draw a box plot we need:

• The median (The middle value)
• The lower quartile (The median of everything left of your median for all the data)
• The upper quartile (The median of everything right of your median for all the data)
• The lowest value and the highest value.

The interquartile range is the upper quartile - the lower quartile

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## Stem and Leaf Diagrams

A stem and leaf diagram is drawn by splitting the tens and units column.

The tens column becomes the 'stem' and the units become the 'leaf'.

The leaf must only contain single digits.

They must be ordered and there must be a key. (e.g. 13|4 = 134)

Back to back stem and leaf diagrams contain two leaf columns (one on either side of the stem) and therefore require two keys.

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## Frequency Diagram

A frequency diagram is similar to a bar chart except the bars are drawn with no spaces between them and the horizontal axis has a continuous scale.

The frequency is plotted vertically / on the left.

The group is plotted horizontally / on the bottom.

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## Line Graph

Line graphs are used in statistics to show how data changes over a period of time. One use is to indicate trends, this could be an upward trend or a downward trend.

It is important to understand that the values between the plotted values have no meaning.

So for example, we cannot definitely state that between Day 1 and Day 2 that the temperature increased steadily. The temperature would've dropped during the night of Day 1 and rose again during the morning and afternoon of Day 2.

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## Frequency Trees

Frequency trees display information that develops or 'branches' off into different groups.

Use the information provided to work out the missing sections.

Slowly section off into different groups.

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## Venn Diagrams

They consist of two or more overlapping circles inside a square where each circle represents a set. ( a set = a list containing things that have something in common.) We use {curley brackets} for sets.

The intersection part represents things which fall into both sets. Things which do not fall into any set are placed outside the circle, in the rectangle.

We can use them to find the LCM and HCF.

• HCF = multiply all the numbers in the intersection.
• LCM = Multiply all the numbers that are within a circle or intersection.

(Diagrams with 3 circles have 2 at the top and one at the bottom.)

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