# Representation of Data

- Created by: eleanor
- Created on: 11-04-15 12:06

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- Representation of Data
- Stem and Leaf
- Advantages
- They still have all details of the data
- They allow direct comparisons of two sets of data
- They give a sense of location and spread

- Key Points
- Always put values in order from the centre
- Make sure values in leaf are always one digit
- Spilt data up to ensure you show a shape
- Always include titles and a key

- How To Read From Stem And Leaf
- Mode = Most Comman
- Range= biggest - smallest
- Median = number of values / 2
- Interquartile Range = Q3-Q1

- Lower Quartile = Number of values /4

- Advantages
- Box Plots
- Advantages
- Shows location and spread at a glance
- Always use clear labels for each box plot and scale

- Outliers
- Are generally found using 1.5 x IQR
- Then subtract from LQ if anything is below this then it is an outlier
- Add to UQ if anything is above this it is an outlier

- Are generally found using 1.5 x IQR

- Advantages
- Histograms
- Key Points
- Histograms are used for continious data
- If a table does not show continuous data you must alter the class boundaries
- Frequencey Density = (frequency /class width)
- The area of the bar is proportional to the frequency
- The modal group is the group with the largest area
- to calculate the height of each bar use the formula k x frequency

- Key Points
- Skewness
- box plots positive: Q2-Q1 < Q3 -Q2
- Negative: Q2-Q1 > Q3 -Q2
- Symmetrical: Q2-Q1 = Q3 -Q2

- Negative: Q2-Q1 > Q3 -Q2
- histograms 3(mean-median)/ standard deviation
- Positive: mode< median< mean
- Negative: mode> median> mean

- Positive: mode< median< mean

- box plots positive: Q2-Q1 < Q3 -Q2

- Stem and Leaf

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