Further2 displaying univariate data

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Further2 displaying univariate data

  1. 1. Further MathsDisplaying Univariate Data K McMullen 2012
  2. 2. Displaying Univariate Data Frequency Table: Used to organise data so that it is more manageable. Frequency can either be counted or taken as a percentage A frequency table displays the data in a compact form and also tells us something about how the values are distributed K McMullen 2012
  3. 3. Displaying Univariate Data Bar charts: used to display categorical data or discrete numerical data The variable is usually plotted on the horizontal axis The frequency (or percentage frequency) is usually displayed on the vertical axis The bars of equal width and have equal spaces between them There is one bar for each category The height of the bar gives the frequency (or percentage frequency) K McMullen 2012
  4. 4. Displaying Univariate Data Segmented bar charts: a variation of the bar chart where the bars are stacked on top of one another to give a single bar with several components. The lengths of the segments is determined by the frequencies The height of the bar gives the total frequency ( total in data set or 100% for percentage segmented bar charts) Should only be used for a relatively small number of components (5 maximum) Percentage segmented bar charts are more useful when comparing bivariate data (two variables) K McMullen 2012
  5. 5. Displaying Univariate Data Dot Plots: Used to display categorical data or discrete numerical data with the variable along the horizontal axis and each dot above it representing one piece of data Best used for small sets of data and when the data values are relatively close together (small range) K McMullen 2012
  6. 6. Displaying Univariate Data Stem plots: each value of the data set it split into two parts: Stem: derived from the first digit(s) Leaf: the last digit The data is displayed in order Always use a key indicating how to interpret the plot K McMullen 2012
  7. 7. Displaying Univariate Data Histograms: Used to display discrete and continuous numerical data and is better used for large data sets as data can be placed into intervals. The variable is usually plotted on the horizontal axis The frequency (or percentage frequency) is usually displayed on the vertical axis The height of the bar gives the frequency The bars have no spaces between them There is one bar for each class interval K McMullen 2012
  8. 8. Displaying Univariate Data Box plots: Used to display numerical data and is a graphical representation of the 5 number summary Displays the location, spread and general shape of a distribution Can be drawn either vertically or horizontally Must always include a scale and the components of the 5 number summary must be clearly labelled Parallel box plots are used when you are comparing different groups (eg. Study scores of males compared to females) K McMullen 2012

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