Geographical Skills

HideShow resource information
  • Created by: lorretta
  • Created on: 12-05-15 20:28
Preview of Geographical Skills

First 361 words of the document:

Lorretta Salkeld 13P
Unit 4 geographical skills
Sampling methods- Systematic sampling
Used when studying areas including environmental gradients
Sample points should be evenly spaced or distributed
It is quick and easy but it is easy to miss variations
Types of systematic sampling
o Point sampling
o Line sampling
o Area sampling
It is more straight forward than random sampling
A grid doesn't have to be used, sampling has to be in uniform intervals
A good coverage of the study area can be more easily achieved than using random
It is more biased as not all members or points have an equal chance of being selected
May lead to over or under representation of a particular pattern
Random sampling
Used where the study area is the same throughout e.g. flat grassy field where I could
assume the environmental conditions are the same so it wouldn't matter where the
sample was taken place
Can be used to choose spots or areas to sample as if choose sample yourself it could be
Random sampling is achieved by generating two numbers from either a random number
table or a scientific calculator and use the two values to make a coordinate and at that
point the sample will be taken from
Random sampling should be free from bias however it is hard to obtain a truly
representative sample.
Large samples are more accurate and representative
Types of random sampling
o Point sampling- grid is drawn over a map of a study area, coordinate is obtained
and sampling is taken place at that point.
o Line sampling- draw a line across a map between two random coordinates that
have been generated, then choose random points along it but there may be big
o Area sampling- dividing areas into sections, choosing random grid numbers but
may lead to empty site sections
Can be used with large sample populations

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Lorretta Salkeld 13P
Avoids bias
Can lead to poor representation of population or area if large areas are not hit by random
sampling, distorting results
Practical constraints- time available and access to certain parts of the study area
Stratified sampling
Is used when the population or sampling frame is made up of sub sets of known sizes
These sub sets make up different proportions of the total and results are proportional and
representative of the whole
This method should overcome the problem with missing…read more

Page 3

Preview of page 3

Here's a taster:

Lorretta Salkeld 13P
Line graphs
Simple line graph- shows single series of data
Comparative line graph- shows two or more on the same graph and use the same scales
Divergent line graph
Easy to draw and understand
Can show both positive and negative values
Displays relative numbers and proportions
Summarises large amount of data in visual way
Easy to spot trends and anomalies
Estimates can be made quickly and accurately
Accessible to wide audience
Often requires additional explanations
Easily manipulated to give false…read more

Page 4

Preview of page 4

Here's a taster:

Lorretta Salkeld 13P
Circle size can also be made proportional to total quantity to compare different
Summarises large data
Easily understood due to widespread use
May not show numerical data
Can get crowded with too many divisions
Categorical data only
Won't know exact values
Easily manipulated
Fails to show cause effects or patterns
Triangular graphs
Percentage and three variables
Example of how it could be used is employment structure so it is divided in to three
sectors- primary, secondary and tertiary
Visual…read more

Page 5

Preview of page 5

Here's a taster:

Lorretta Salkeld 13P
Can show previously unseen patterns e.g. log graphs show increase in world population to
be slowing down, normal graphs do not show this slow down.
Cannot start from 0
May make some relationships appear different as parabolic curves on a normal graph
become straight on log graphs
Kite diagram
Shows changes over distance
Show presence/absence of species along a transect, Thickness shows no.…read more

Page 6

Preview of page 6

Here's a taster:

Lorretta Salkeld 13P
Measured over a set period of time
Strong visual impression of both volume of movement & direction
Parts of the map may be obscured/crowded and difficult to interpret
Not appropriate for lots of variables
Desire line
Shows the strength of people who move from point A to point B, C or D on a map
Thickness of the line is proportional to the number of people
Visual impression of movement from areas to a point
Easy to interpret
May…read more

Page 7

Preview of page 7

Here's a taster:

Lorretta Salkeld 13P
One variable only
Inexact ­ not the actual data
Isoline map
Maps showing lines drawn through points of equal value
Often used with colour between isolines to more clearly depict trends
Show more gradual change than choropleths ­ avoid abrupt change
Can clearly see boundaries
Show gradients
Trends are shown clearly
Whole numbers, percentages and ratios can be used as long as the data is point data
Unsuitable for showing discontinuous data
Shading may imply equal value between lines
If…read more

Page 8

Preview of page 8

Here's a taster:

Lorretta Salkeld 13P
Testing for a relationship between two variables
If number is above critical value must accept the alternative hypothesis- there is a
If number is below the critical value, accept the null hypothesis- there is no relationship
Formulate a null hypothesis individually rank values of each variable find the
difference between the 2 square the differences sum the values input into the
Assesses statistical relationship between 2 variables.…read more

Page 9

Preview of page 9

Here's a taster:

Lorretta Salkeld 13P
Can't be used if there are less than five sets of data
Uses ranking so loses raw data
Chi Squared
Null hypothesis ­ `no relationship between distribution of... and of...'
Subtract observed frequencies from expected
Square result
Divide this by the expected value for that group
Compare with degrees of freedom: on the critical value chart, the degree will be one less
than the total no. of observed values
Can test association between variables.…read more

Page 10

Preview of page 10

Here's a taster:

Lorretta Salkeld 13P
10…read more


No comments have yet been made

Similar Geography resources:

See all Geography resources »See all resources »