Geography Fieldwork Statistical Methods and Tests
Statistical methods and tests include:
Box Plot Constructor
Box plots or box and whisker charts are a good way to display a range of information about your data sample. These plots contain the range, interquartile range, median, lower value, upper value, lower quartile, upper quartile and standard deviation. Box plots or box and whisker charts can be constructed for different sample sets to compare distributions.
Beach Profile Cross Sectional Area and Beach Volume Calculator
Make a beach profile and calculate the cross sectional area and beach volume using cumulative distance and slope angle or height change data.
Cailleux Roundness Index
Calculate the Cailleux Roundness Index for each pebble or sedimentary particle and create a box plot to analyse the results.
Coding is a process in which quantitative or qualitative data is categorised to help analysis. This can be used by geographers to help analyse questionnaires results, newspaper articles or interview transcripts.
Mann Whitney u Test
A Mann Whitney u Test example deals with two sets of sample data from two contrasting urban areas, area X and area Y, with the aim of comparing them and demonstrating differences. Tests of significance are used to tell us whether the differences between the two sets of sample data are truly significant or whether these differences could have occurred by chance.
Our River Cross Section Calculator uses Manning’s n to calculate flow velocity on intermittent and ephemeral streams. Manning’s n predicts the degree of roughness in river channels. Flow velocity is strongly dependent on the resistance created by channel roughness. An increase in the Manning’s n value will cause a decrease in the velocity of stream flow.
Nearest Neighbour Analysis
Nearest Neighbour Analysis is used in the search for order in settlement or other patterns in the landscape. This attempts to measure the distributions according to whether they are clustered, random or regular.
River Cross Section Calculator, including hydraulic radius and wetted perimeter
Enter your river data to quickly make a river cross section and calculate the cross sectional area, wetted perimeter and hydraulic radius. Discharge may be calculated by entering the average river velocity. For intermittent and ephemeral streams, channel gradient and Manning's n can be entered in the calculator to calculate the discharge.
The larger the size of the sample, the greater is the probability that it accurately reflects the distribution of the parent population. The example shows how many pebble long axes are required to be measured at a beach site to obtain an average (or mean) at the 99% confidence level.
Simpson's Diversity Index
A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance. Simpson's Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases.
Spearman's Rank Correlation Coefficient
The Spearman's Rank Correlation Coefficient is used to discover the strength of a link between two sets of data. An example looks at the strength of the link between the price of a convenience item (a 50cl bottle of water) and distance from the Contemporary Art Museum in El Raval, Barcelona.
Spearman's Rank Correlation Coefficient Rs and Probability (p) Value Calculator
The Spearman's Rank Correlation Coefficient Rs value is a statistical measure of the strength of a link or relationship between two sets of data. This calculator generates the Rs value, its statistical significance level based on exact critical probabilty (p) values, scatter graph and conclusion. Spearman's Rank has many common uses in geography including the analysis of changes in economic, social or environmental variables over distance along a transect line, or questionnaires with Likert scales.
The standard deviation is a statistic that tells you how tightly data are clustered around the mean. When the sizes are tightly clustered and the distribution curve is steep, the standard deviation is small. When the sizes are spread apart and the distribution curve is relatively flat, that tells you that there is a relatively large standard deviation. A data set with less extreme values has a more reliable mean. The standard deviation is therefore a good measure of the reliability of the mean value. Our Box Plot Constructor calculates the standard deviation for a data set.
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