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B .A. / B.Sc. (Hons) III Semester (CBCS) GGB3P1: STATISTICAL METHODS IN GEOGRAPHY UNIT 1: USE OF DATA IN GEOGRAPHY Topic: Geographical Data Matrix (GDM) Statistics is a branch of science that deals with the collection, organisation, analysis of data and drawing of inferences from the samples to the whole population. This requires a proper design of the study, an appropriate selection of the study sample and choice of a suitable statistical test. Or Statistics is the science of quantitative data. According to Seligman, “ Statistics is the science which deals with the methods of collecting, classifying, presenting, comparing and interpreting numerical data collected to throw light on any sphere of enquiry”. The statistical method is a comprehensive term which includes almost all methods involved in collection, processing, condensing, analyzing, presenting and interpreting the data. Geographical Data Geographical or spatial data are defined as undigested, unorganized, and unevaluated material that can be associated with a location. Geographical data include facts, results of observations, original remote sensing images, basic census figures and statistics all of which are gathered and communicated to the user. Data are of little value in or of themselves. To be useful they must be transformed into information. When data are organized, presented, analyzed, interpreted and considered useful for a particular decision problem, they become information. Accordingly, geographical information is defined as georeferenced data that have been processed into a form that is meaningful and of real or perceived value to decision makers. Forms of Geographical Data Document form • Text Paragarph Numeric Form • Table • Semi-table Digital Form • Digital data of aerial photographs • Digital data of satellite imagery • Graphs Graphical Form • Diagrams • Areial Photographs • Satellite imagery Geographical Data Matrix (GDM) Geographic data posses two distinct components- Location and attributes at locations, and the geographical data matrix is perhaps the most logical way to represent the real world. It is a major milestone in the development of data organization methods in scientific geographical studies. In the GDM, a column represents the variation of attributes of the natural or socio-economic characteristic across some geographical spaces. Thus, basically it shows spatial pattern of the variables that can be identified and mapped. A row, on the other hand, denotes a specific location in geographic space. Therefore, each cell formed by the rows and columns of GDM contains a specific item of geographic fact that can be found at a particular location. In a GDM, the column can be compared to study the nature of spatial variation of the geographic characteristics. Dimensions of Geographic Data Data Source: 1. where are the data coming from? 2. Who colleted it? 3. Who distributed it? 4. What collection methods were used? Location: to where do the data pertain? Level of aggregation: are the observations individual entities or groups of entities Decimals- are the data values discrete or continuous? Descriptive vs. measured: are the data numerical or categorical? Example: To be analysable with statistical tools, data needs to be presented as a rectangular data matrix. Each column in a data matrix contains a variable (indicator, measurement, questions in a survey...) and each row an observation (case) ROW Country Name GDP Literacy Rate n A Value Value olum B Value Value C C Value Value D Value Value
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