First 305 words of the document:
Geographical skills theory
Data analysis- Methods to display a basic description of data
Measures of central tendency
These are used to calculate the average in a set of data. They can be very useful
when trying to identify simple differences between the sets of data.
Mode is the simplest method which shows the most frequently occurring
Median is the middle value of the data when all items have been placed in
order from lowest to highest value.
Mean is the most useful method of central tendency and the only one that
requires a calculation. The mean is calculated by adding all the values in a
data set together and dividing by the number of values there is in that data
Standard deviation involves a calculation and looks at the variation of all
the data from the mean. The larger the standard deviation the larger the
variation around the mean. This is useful when comparing two data sets with
a similar mean, but is more complex and requires a formula and a
Measures of dispersion
Data sets vary in terms of how they are scattered around the average. Dispersion
is the various different measures which indicate the extent to which data is
grouped around the mean.
Range is the simplest way to look at the spread of values in a data set. This
can be misleading if the highest and lowest values are extreme.
Interquartile range is an improvement on the range as it takes the range of
the middle half of the data range either side of the median. It is quick and
easy to calculate and avoids the distortion caused by extreme values.