Geographical skills Geographical skills Planning an investigation Data Primary data Unprocessed information that has not been analysed or interpreted in any kind of way Advantages- reliable, not biased or invalid Disadvantages- time consuming, unreliable or invalid due to human error whilst collecting and using poor equipment Secondary data Information that has been analysed and interpreted Advantages- quick to collect, more reliable of from a well known source Disadvantages- biased, can’t be certain if the reliability and accuracy of methods used to collect it. Sampling Sampling size Point- sample taken at given point such as coordinates on a map Linear- given points along a line or transect that has something alike such as along sand dunes Areal- given area such as a quadrat to measure vegetation cover or on a grid square on a OS map Sampling method Random sampling Using number tables to randomly generate a number to select a sample Advantages- statistically sound so could lead to further analysis Disadvantages- same item could be picked more than once, easy to miss something Stratified sampling Take account of underlying patterns in data and ensures all are sampled Advantages- ensures no significant aspect is missed Disadvantages- data collection is biased, can’t make valid statistical differences Geographical skills Systematic sampling Item is selected at regular intervals Advantages- easy to do, quick Disadvantages- interval may coincide with in the data or location, can’t make valid statistical inferences Pragmatic sampling Sample where you can get access and where changes are observed such as troughs and crests of a sand dune system. Advantages- safe realistic Disadvantages- can’t make valid statistical inferences, not a fair sample Location The exact boundaries for your location need to be specified in the planning stage Location needs to be accessible, safe, and realistic in order to improve accuracy of results. Time Enough time must be provided to complete investigation accurately Creating a time plan of the day of investigation will help to know how much time you can spend collecting data at each transect. Risk assessment It is important to think of any potential risks that could be involved in collecting your data and what strategies you could use to prevent them or reduce the risk of them occurring To calculate the total risk you should identify the likelihood of the risk occurring and the severity of that risk. Likelihood and severity are rated from 1-5, 5 being the worst and these are multiplied together to calculate the risk involved. A pilot study should be used to allow you to visit the location before the day of investigation to help identify potential risks. Geographical skills Hypothesis features Features of a hypothesis Simple- single question not multiple questions Measureable- contains units that can be measured Achievable- can be investigated with the location chosen, time, resources and equipment available. Realistic- can it be done? Avoid ‘what if’ questions as they are hard to prove Timed- how much time is needed for the investigation? Research best carried out over a short time frame with short intervals. Other features Suitable scale- small scale is better than large scale as they are more accessible Readily researched- some topics can’t be researched effectively due to: Time needed Number of researchers needed Data being unavailable Clearly defined- terms understood to avoid confusion Clear geographical nature- spatial or locational Based on wider geographical theories, ideas, concepts or processes Clear aim- single purpose and focus on research allowing clear conclusions to be stated. Geographical skills 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 value. 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 set. 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 calculation: 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. Geographical skills Frequencies Frequency diagrams are useful to plot the distribution of values in your data set. They give a good visual representation of whether the 2 sets are different and allow frequencies to be compared. Skew is a term used to describe the distribution of data. Data is skewed if the distribution isn’t symmetrical. If the mode is lower than the mean it is negatively skewed and if it is higher than the mean then it is positively skewed. Kurtosis describes the amplitude of the data or its shape. Distributions can be peaked, flat or in between. Measurement of patterns These tests are used to measure whether a pattern exists and what type of pattern it might be. Nearest neighbour This involves comparing the observed spacing of a set of points and the spacing that would be expected if the pattern had been random. This technique relies on measuring the distance between neighbouring points usually on a map. The observed spacing is expressed as the distance of all points from their nearest neighbour in straight line measurement. Lorenz curve This technique is a measure of the degree of concentration of points. These curves are used in economic geography, on data linked to areas and involve the comparison of percentage frequencies. Geographical skills Presentation Types of data Discrete data- data with distinct separate parts Ordinal data- data that has an order Continuous data- data where there are no breaks but instead something happens continuously. Areal data- data that applies to an area rather than a point or an individual Time series data- data where something occurs at intervals Period data- data where a phenomenon repeats it’s self at intervals Factors to consider when selecting a technique to present your data factors Scale/interval location Size of symbol shading colour lettering dimension key Legend or caption scale Comment If the scale is too big it will hide patterns If the scale is too small, it will take too long to make and could produce complex patterns that are hard to interpret. Figures have a clear scale with no overlapping values Scale always starts at 0 Where should the figure be placed to represent the area it applies to best? Make sure comparative diagrams are the same scale Symbols shouldn’t be too large or else they can overlap or hide information on the map. They mustn’t be too small or else they can be hard to see or may be read incorrectly Should always get darker as the value increases, white will apply to their being no data. The shade should always be of the same colour. Colour should be avoided as it is difficult to compare colours. However, colour can be useful when comparing patterns Varies in alignment, size, spacing and style. Shouldn’t obscure data and should be able to be reads easily, similar sizes should be used on one technique of presenting data 3D can cope with higher values, but the value is proportional to its value so this involves careful calculation and it may mislead visually by looking less than it actually is All maps and diagrams should have a clear key, and should be located in a clear location on your map or diagram All diagrams and maps should have a title and figure number All maps should have a scale Geographical skills Data presentation- non spatial data Tables- effective, simple, good for showing a large amount of data in a concise way. However, they have little visual impact. Diagrams- use images. Pictograms use symbols to represent values. Display data in a simple and visually stimulating way. Can be exaggerated or distorted and give vague displays of data. Charts- more precise than tables or diagrams and are available in a vast variety of forms. They are forms of proportional symbols as their length, area or volume is proportional to the value of the data. They are easily available on computer programs and are visually stimulating. Bar chart- used for discrete or time series data. Simple, quick and give an instant visual impression. Can be vertical or horizontal. Length of the bar is proportional to its value. Width of bar can be misled over the value represented by the bar. Gaps should be left between the bars or else the chart is called a histogram. Pie chart- used with percentage data to show parts of a whole set of data. Visually stimulating. Too many sectors can make it look unprofessional. Hard to use colours as they distract from the sector size. Difficult to label sectors so they are easy to read. Only useful for percentage data. Divided bar chart- used to show constituents of a whole. Must keep the divisions in the same order if you want a comparison. Too many sections makes it look unprofessional. Difficult to use lots of colours, not always easy to compare. Rose or star- used to show directions. Length of bar reflects frequency and width. Time consuming to draw and takes time to read as 2 aspects are shown. Proportional circle, square, triangle- area of shape is proportional to the square root of the data value. Can cope with large numbers. Time consuming to calculate and draw. Not easy to compare accurately, scale complex to draw. Proportional sphere, cube or pyramid- area of the symbol is proportional to the cube root of the data value. Copes with very large numbers and gives a good visual appearance. Time consuming to calculate and draw. Not easy to compare accurately, scale complex to draw. Geographical skills Graphs- ideal of continuous data or when looking for patterns between 2 or more variables. The X axis has the independent variable and the Y axis has the dependent variable. The graph shows to what extent X causes or influences Y. Types of graph include: line graph, scatter graph, multiple line graph, triangular graph, compound graph and positive or negative graph. Geographical skills Data presentation: spatial data Maps - relevant features and data are marked on a map. Need a suitable scale, title and north to be indicated. Isolines - uses point data by drawing a line to join up the points of the same value, the lines represent the same value at the points in an area through which it passes. Advantages- drawn easily on computers, can see areas of equal value, can see gradual changes, avoids problem of boundary lines Disadvantages- don’t show discontinuous distributions, only work where there is enough data spread over the area and when the changes are gradual. Choropleths - density maps where areas are shaded to represent the average number per unit area. Advantages- visual impressions of change over a space, general anomalies can be identified, easily done by computer or hand, doesn’t breech data protection, good for data that involved density reading, easy to interpret via a key. Disadvantages- general, gives false impression of an abrupt change at boundaries, variations within each area are hidden, reading exact figures is impossible Located symbols- dot maps Advantages- effective in showing spatial density, shows variation and pattern, easy to interpret, purpose is easily understood, easy to generate in a computer. Disadvantages- actual values can’t be seen, dot crowding can lead to clustering which is not very accurate, time consuming if done by hand, easy to make a mistake Located symbols- proportional symbols Advantages- can deal with larger numbers than dots Disadvantages- size of circles (too small and they can be hard to see, too large and they can cover the map), scale (need a scale proportional to the square root of the data value), location of circle (hard to be precise so it can be inaccurate). Geographical skills Located symbols- combined dots and circles Advantages- good where low and high values are concerned Disadvantages- confusing and difficult to read exact numbers, needs complex scale, location of symbols Located symbols- located bars Advantages- simple and quick, easy to compare, can subdivide the bars to show other features Disadvantages- size of bar can hide detail on the map, bars can extend over boundaries causing confusion, and location is hard to see as the bar is large. Flow lines Advantages- immediate visual impression, show movements easily, gives clear sense of direction, clear spatial component Disadvantages- hard to draw, can be in the same direction or overlap, hard to show meeting point of wide bands without overwhelming the map Trip lines type of flow line that shows direction and volume of movement but are straight line drawings Sketches Advantages- give a good visual impression and shows main features clearly Disadvantages- must be used effectively to be of any use or else they are a waste of time, must be correctly annotated Photographs Advantages- set context of investigation, analyse area in detail after day of investigating- more detail can be found when analysed in a lab Disadvantages- must be annotated to be effective Geographical skills Analysis of data- qualitative data and quantitative data Qualitative data subjective description in words influenced by an individual’s opinions and beliefs. A scatter graph is used to see if there is a link between 2 variables. A correlation is either positive or negative. If there is no correlation then the variables aren’t linked. Quantitative data statistical data consisting of numbers. To establish clear links statistical analysis is used to identify trends, groups and anomalies. They show if a relationship really exists and the strength of that relationship. When doing statistical analysis... Keep it simple- use simple methods of analysis to start with as they often show results without the need of complex calculations Remember your hypothesis and choose a correct method to suit this. Work towards a 95% significance level. This means that you can be confident that anything above or on 95% is significant and anything below is not significant. Check you have the formula correct as most errors are made through small mistakes in calculations. Analysis of data Qualitative data Data is a subjective description in words which varies depending on who is recording it (it is open to interpretation) such as a description of housing quality In its simplest form this could be an analysis of some graphs. This is quick, visual and shows the obvious anomalies. One of the simplest approaches to qualitative analysis is to see if two variables are related by using a scatter graph. A line of best fit will show the correlation between the two as either a positive or negative correlation. If there is no correlation then the two variables aren’t linked. Geographical skills Quantitative data Statistical data which consists of numbers. It is objective and should be value free. When there is no clear trend or link between two sets of data the analysis of data can be taken into further detail with statistical analysis. They can identify trends, groups and anomalies as well as predictions from larger sets of data that is too complex to be analysed by using qualitative analysis. Statistical analysis is useful as it shows whether a relationship really exists as well as the strength of the relationship. It can also simplify large sets of data into a single result that can give a measure of its level of accuracy and reliability. A few things to think about when doing statistical analysis: Keep it simple- don’t do statistical analysis for the sake of it and start off with simple methods of analysis as often the result is clear without the need for a mathematical calculation. Remember what your hypothesis is in your investigation and choose the correct statistical methods to suit this. Remember that you need to work towards a 95% significance level. This means that you can be confident that anything above or on 95% is accurate. Anything less is inaccurate. Check you have the formula correct, as most errors are made by small mistakes in the actual calculation. If you don’t understand how to do a technique or what the technique shows then don’t use it. Geographical skills GIS Geographical information system GIS is a computer tool used for storing, organising, displaying and analysing geographical information. It allows data to be located to any spot on the earth’s surface. It can be used for things such as field samples, aerial photography, land surveying, GPS, population census and administrative records. Advantages Can cope with large amounts of data Can cope with wide variety of data Can cover large study areas Can change scale of an area Dynamic so can cope with frequent changes Easier to keep up to date so findings are current Fast and efficient Avoid political boundaries and other practical boundaries to research GIS can be used in geographical investigations: Stage 3 collecting and recording data: can be used in the field to measure and record information as it can be linked to a specific point. E.g. weather monitors can collect information and transfer them to GIS. Also used to measure distances in a straight line more accurately than on a map. Secondary data can be accessed from several sites through GIS. Stage 4 analysing and interpreting data: allows you to ask questions such as “where is?” and “what if?” Possible to measure distances between locations hence giving exact measurements. Raster analysis: GIS can store data as a grid. Geographical skills Statistical testing These tell you if there is a difference or correlation between 2 sets of data as well as saying the degree of the difference or correlation. Mann Whitney U test Tests the difference between medians of 2 sets of data and can be used when the data is in an awkward form such as with samples of very different sizes. Advantages: Shows the median between 2 sets of data Good at dealing with skewed data You can decide the boundaries of 2 groups Disadvantages More appropriate when the data sets are independent from each other More appropriate when both sets of data have the same shape distribution Have to have equal sample sizes Spearman’s rank Used when both sets of data can be easily ranked, when a quick and easy measure of correlation is needed and where exact values may be uncertain. It indicates if 2 sets are related. To be significant the end value must be at or above 95% significance level. Advantages Shows the significance of the data Proves/disproves correlations Allows for further analysis Disadvantages Can be difficult to work out Quite a complicated formula Can be misinterpreted Geographical skills Chi squared test Used when data is in categories or when it can be grouped into categories i.e. when it is nominal. It tests the difference between the observed pattern and the expected pattern from chance events. Advantages Can test associations between variables Identifies differences between observed and expected variables Disadvantages Can’t use percentages Data must be numerical Categories of 2 are not good to compare The observations must be 20+ Quite complicated to get right due to difficult formula Geographical skills Testing for relationships and correlations There are three types of correlation or relationship, these are; positive correlation (when one value increases so does the other), negative correlation (as one value decreases so does the other) and no correlation (there is no link between the two values, so they do not influence each other). Statistical tests are used to find out the type of correlation but also the strength of that correlation. To be confident of a significant relationship you must be at least 95% or above certain that the null hypothesis can be rejected. Spearman’s rank Used when both sets of data can be easily ranked, a quick and easy measure of correlation is needed and where exact values may be uncertain. This calculation can indicate if two sets of data are related. A scatter graph can be drawn first to give a rough idea f the expected result. These can show you if the correlation is positive or negative. Firstly data must be ranked, and must be ranked in an appropriate way to suit your null and alternative hypotheses so from either smallest to largest or vice versa. The result will lie between +1 (a prefect positive correlation) and -1 (a perfect negative correlation) with 0 representing no correlation. The exact significance of your result is checked by looking up the result in a table of significance. However spearman’s ranks shouldn’t be used when there are a lot (more than 4) sets of tied ranks; where there are a limited number of data sets as usually at least 8 are needed and where two data sets are unequal in number. Chi squared test This is most useful when your data has been collected in categories or when you can group it into categories (when your data is nominal). It tests if there is a difference between the observed pattern and the expected pattern from chance events. For the test to be valid, the total number of observations should be more than twenty.