1.2. Graphical Presentation Flashcards
Descriptive statistics (graphically)…
Summarise a mass of information graphically in a clear, concise and accurate manner.
Bar charts…
The value of each category in categorical data is represented by a bar.
Can also represent the frequency of entities in a category.
For example, median gross weekly earnings for employees in Scottish cities.
Cluster bar charts…
Used to make comparisons between two types of data.
For example, median gross weekly earnings for male and female employees in Scottish cities.
Truncated axes…
A common problem whereby bar charts do not begin on 0 on the Y-axis.
When axes are truncated, the bar charts do not give a true picture of data that is being analysed.
Pie charts…
Used to describe the distribution of data within a data set.
The area of each section represents the relative frequency.
For example, the market share of supermarkets in the UK.
Histograms…
Shows data summarised in frequency density.
Frequency density = frequency / class width.
Provides information about distribution as it accounts for class widths.
Therefore, have a different shape to bar charts, unless class widths are all identical.
Skew of data…
If more data is on the right, data is skewed to the left.
If more data is on the left, data is skewed to the right.
If data is not skewed, it is symmetrical.
Ogives…
A cumulative distribution plot.
It is a distribution curve in which the relative frequencies are cumulative.
