Graphical Skills Flashcards
When should you use a Scatter Graph?
To show a relationship between two continuous variables
Give a strength of a Scatter graph.
Shows a relationship between two variables
Can show exact data
Give a weakness of a scatter graph.
Only compares two variables
Don’t know the strength of the relationship without a statistical test
When should you use a Bar Graph?
X axis = discrete data; Y axis = continuous data// compare categories
Give a strength of a Bar graph.
Show discrete data - absolute values
Shows and can compare multiple categories
Can show large data sets
Give a weakness of a Bar graph
Doesn’t show relationships between categories and only show discrete categorical data
Located:
Position of the located symbol may obscure data on the base map
Located bars may begin in one are of the map and end in another creating confusion
When should you use a Pie chart?
To show data as a percentage of a whole
Give a strength of a pie chart.
Shows percentage total for each category
Give a weakness of a pie chart.
No exact numerical data - so don’t know the total
Only show discrete (categorical) data
When should you use a Line Graph?
Values plotted and joined by a line; compare continuous variables; multiple lines for multiple data sets
Give a strength of a Line graph.
Show all data points - exact data
Shows range, min, max and anomalies easily
Can predict the future
Multiple data sets can be displayed on one graph
Give a weakness of a Line graph
Can only use continuous data
Can be unclear if too many data sets used
When should you use flow lines?
Show volume (width of the line) and direction (arrow points in direction) of movement
Give a strength of flow lines.
Shows volume and direction
Show absolute and percentage values - by width of the line
Can show actual routes or be simplified to show the general straight line
Give a weakness of flow lines.
Can overlap - be unclear
When should you use desire lines?
Shows direction and movement (straight line joins places of origin and destination)
Give a strength of a Desire lines.
Shows direction
Visual and clear
Give a weakness of a desire lines.
May overlap and be unclear
Don’t know volume of movement
When should you use a Radial diagram?
Central point data radiates outwards
Show relationship of a multiple variables to the central point
Show multiple variables of continuous data
Give a strength of a radial diagram.
Show relationship of multiple variables to the central point
Can be used to show direction (e.g. if points of the compass used)
Trends in data clearly shown - variable with largest value highlighted
Give a weakness of a radial diagram
Limited data applicable to this method
Difficult to read exact values from the scale on the axis as often diagram is too crowded to include a scale
Difficult to find a suitable scale when data has a wide range of values.
When should you use isolines?
Line joins data points of equal value e.g. contour lines on a map; isovel (equal velocity in a river); isobars (same air pressure); isopleth (points of the same value)
Give a strength of isolines.
Show data and distribution
Shows areas of equal value
Shows gradual change
Give a weakness of isolines
Don’t show discontinuous distributions
Need gradual changes - otherwise lines too close and unclear
