Geography 4A Skills
- Created by: MrMeeb
- Created on: 04-02-17 16:31
Line Graph
Aim: Method to show continuous data
Advantage:
- Can easily show trend over time
- Can be used to predict future trends
- Can be used to compare data
- Can be used to estimate for points we don't have data for
Disadvantages
- Scale must be done carefully, and can distort results, making comparison misleading
- Can only be used with continuous data
Compound Line Graph
Can be used to show multiple pieces of information, and generally needs two vertical/horizontal axis - climate graph
Divergent Line Graph
Can go into positive and negative values - either size of axis - temperature variation
Bar Graph
Represents the number within a set of data, like a category. Can be used to compare different data sets of categories within a data set
Advantages:
- Visually strong - easy to use
- Allows easy comparison
- Easy to draw
- Shows trends better than tables
Disadvantages:
- Can be reorganised to emphasis certain things - may impact conclusion
- Only uses discrete data (data that can only take certain values)
- Only shows patterns
Divergent Bar Graph
Bars can go either side of the axis - population pyramid
Scatter Graph
Shows two sets of data plotted against each other - shows a relationship between two variables. The line of best fit represents the direction and nature of the correlation
Advantages:
- Lots of data can be plotted into a small space
- Patterns can be identified quickly and evenly
- Retains exact data values
- Anomalies easily seen
- Shows what type of relationship exists
Disadvantages:
- Data needs to be continuous
- Can only compare two sets of data
- Mistakes easily made with large data sets
- Line of best fit can show misleading relationship
- Doesn't show how strong the relationship is - relies on Spearman's Rank
Pie Chart
Displays data components of a whole data set, shown as segments and percentage values
Advantages:
- Good visual representation
- Shows percentage total for each category
- Can be easy to compare
- Can be used effectively on a base map
Disadvantages:
- Too many categories make them hard to interpret
- Too few make them too simplistic
- No exact numerical data
- Use only with discrete data
Triangular Graph
A graph with three axis. Figures of each data set must be percentages
Advantages:
- Useful in showing patterns of clustering between three variables
Can plot many data points
Disadvantages:
- Very limited use - have to be three data sets
- Does not have a spatial element - can't be placed on a graph
Radial Diagrams
Radial Diagrams
Plot data in a circular fashion around a central point
Advantages:
- Specific technique and effective way of presenting data on wind direction frequency
- Polar graphs - effective at showing change over time
Disadvantages:
- Can only be used on limited types of data - change over time or direction
- Polar graphs distort higher values, making it slightly harder to interpret
Box and Whisker Plot
Allows you to see the spread of data. Can be used to compare data if the same scale is used
Advantages:
- Useful visual representation of dispersion in data
- Can compare different data sets
Disadvantages
- Time consuming to plot more than one data set
- Does not give a numerical value of dispersion
Logarithmic Scales
Specialised version of a line graph - the scale increases in multiples of ten
Advantages:
- Good way of displaying a large range of data
- Shows the rate of change in data
Disadvantages:
- Zero cannot be plotted
- Negative and positive values can't be on the same graph
- Very easy to make mistakes on a large graph
Kite Diagrams
Good at displaying change in percentage over a distance
Advantages:
- Visual representation of plant coverage at various stages - width of kite represents the amount
- Allows easy comparison between multiple kite diagrams
Disadvantages:
- Very specific and works with a limited data range
- Can be easily affected by anomalies
Remotely Sensed Data
Use of technology to gain data - photographs, digital satellite images
Advantages:
- Can remind you of an area when you leave
- Good overview of satellite images
Disadvantages:
- Can crop out things accidentally
- Photo can be overcrowded
Use of Databses
Using things like a census as secondary data
Advantages:
- Large amount of data available in various resources
Disadvantages
- Time consuming to find data needed
- Need to be clear about the data you're trying to find, or you'll get vague results
- Census data is gathered every 10 years - large gaps
GIS
Integrates hardware, software and data in a presentable fashion good for analysis
Advantages:
- Allows recognition of patterns
- Can access data regarding these patterns - maps can hold data
Disadvantages
- Technology required is very expensive - digital cameras and satellites and software
- Time consuming to input data
Interquartile Range
To calculate lower quartile (when n is the number of values)
(n + 1)/4
To calculate the upper quartile
((n + 1)/4) x 3
To get interquartile range, subtract the upper from the lower
Advantages:
- Gives a mathematical figure to show dispersion
- Simple to calculate
- Not affected by anomalies
Disadvantages:
- Works alongside median - not the best at finding central tendency of a data set
Standard Deviation
Calculates a figure that shows the extent that the data is clustered around the mean - a larger figure means a wider spread around the mean, and less reliable.
Once calculated, add the value to the mean and also subtract it from the mean to find the two values that 68.2% of results sit between. The smaller the range, the better
Spearman's Rank
Common technique for measuring correlation strength. The ideal data set is more than 10 and less than 30 pairs of data
Advantages:
- Shows the strength of a relationship
- Can test its statistical significance (how likely the result you got is random (lower chance is better))
Disadvantages:
- Illogical variables can still show a correlation
- Not reliable with less than 10 values
- Hard to do with more than 30
- Does not imply a casual relationship - a change in one WILL result in a change in the other
Chi-squared
Examines what you expect to find in your study and what you actually find, and also tests the significance of the results
Advantages:
- Can be applied to large data sets
- States whether the difference is statistically significant
- Easy to interpret and use the figure
Disadvantages
- Data must be displayed as frequencies, not percentages
- Does not tell you the nature of the difference between expected data and observed data, just that there is one
- Must have a fairly large data set
Mann Whitney U Test
Assesses the possibility of the difference between the two sets of data being as a result of chance or fluke. The data is assumed to not be normally distributed and can be ranked. There must be fewer than 20, and more than 5 samples
Advantages:
- States whether the difference is the result of chance
- Can be used for smaller data sets than Chi-Squared
- Easy to interpret and use
Disadvantages:
- Not good with large sets
- Does not tell you nature of difference, just that there is one
- Must have a small-ish data set
Chloropleth Map
Use a system of colours/shades to show patterns on a map that may be otherwise hidden in numerical data
Advantages:
- Can show a clear pattern that may not be clear with just numbers
Disadvantages
- Does not show regional variation
-Assumes there is an abrupt change at boundary lines, when it's probably gradual
- Too large a class interval means a lot of places will be the same shade, even if values aren't too similar
Dot Maps
A dot is placed for each feature on a map of relevance e.g arable farms in the South of England. Can be used with a scale
Advantages:
- Can show exact location of feature
- Can easily show patterns and clusters
Disadvantages
- Dots don't show exact values
- Can very easily become overcrowded
- Scale of map is important
Isoline Maps
Isolines are lines that represent the same value along their whole length, like contour lines or isobars
Advantages:
- Shows a clear pattern
- Actual values can be identified
Disadvantages
- Anomalies can affect map and have to be removed, meaning it isn't a direct reflection
- Can become overcrowded if overly detailed
Desire Lines
Lines that show the quickest path from origin to destination (as the crow flies). Thickness is proportional to how many people/things travel from origin to destination
Advantages:
- Show a clear pattern
- Can determine approximate values
Disadvantages:
- Hard to ensure exact values
- Does not show the actual path travelled
Flow Lines
Used to show the actual flow and direction of something. The lines are proportional to the number traveling along the route
Advantages:
- Can calculate exact values
- Can use percentages
- Shows direction and volume
Disadvantages:
- Need at least a local scale map - can't be done on a large scale
Trip Lines
Similar to desire lines, except there is no thickness as the amount of people that travel from origin to destination is not presented
Advantages:
- Shows a clear pattern
- Easier to draw as lines don't need scale
Disadvantages:
- No exact values
- Doesn't say how many times journey is taken
OS Maps
Can be used as a base map or on its own. Shows how the land is being used, and the presence of human or physical features
Maps with proportional symbols
Base maps with symbols added that proportionally represent values at the location they are linked to
Advantages:
- Allows comparison of areas
- Allows recognition of patterns
Disadvantages:
- Can become too cluttered easily
- Too little information can make it less useful
Sketch Maps
Maps drawn quickly but carefully at the location
Advantages:
- Can be used to get a general idea of the area when leaving it
- Can be used as a base map
Disadvantages:
- Can be misleading if not drawn correctly
Town Centre Plans
Very detailed diagrams of central area land use
Advantages:
- Gives a good, accurate presentation of land use in a central area
Disadvantages:
- Elements can be vague, like labels
- Can get out of date very quickly
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