GEOGRAPHICAL STATISTICS GE 2110 Zakaria A. Khamis Introduction to Geographical Statistics • The study of geographical phenomena often requires the application of statistical methods to produce new insight • Methods of statistical analysis pay a central role in the study of geographic problems • What are the effects of global warming on the geographic distribution of species? • Such question make use of statistical analysis to arrive at the conclusion 3/15/2016 Zakaria Khamis 2 • The role of statistical analysis in geography may be placed within a broader context through its connection to the scientific method • GEOGRAPHY !!!! Is it art or science? • Scientists (social and physical) make use of scientific methods in their attempts to learn about the world CONCEPTS THEORY 3/15/2016 DESCRIPTION LAWS Zakaria Khamis HYPOTHESIS MODEL 3 • Laws are universal statements of unrestricted range • Theories refer to collection of generalization (laws) Einstein called theories ‘free creation of the human mind’ • Statistical methods allow us to suggest and test hypothesis using models • Geographers use spatial analysis within the context of the scientific method in at least two distinct ways • Exploratory methods of analysis are used to suggest hypothesis 3/15/2016 Zakaria Khamis 4 • Confirmatory used to help confirm hypothesis; however, it does not always confirm or refute hypothesis • STATISTICS historically, it was a branch of political science dealing with the collection, classification and discussion of facts bearing on the condition of state or community (Hammond and McCllagh 1978); e.g. in todays situation is vital statistics • McGrew and Monroe (2000) define statistics as the collection, classification, presentation and analysis of numerical data 3/15/2016 Zakaria Khamis 5 • Is a science of organizing, assembling and anlysing data as well as drawing conclusion about what the data means. • Is a science of observing, collecting, recording, summarizing, analysing and presenting data in organized way. • Modern defintions have in common the objective of inferring from a sample of data the nature of a larger population from which the sample was drawn 3/15/2016 Zakaria Khamis 6 Branches of Statistics Descriptive: Aim to summarize and describe the data .It is a straightforward presentation of facts in which a desicion have been made. Numerical (mean, mode, median etc) and graphic approch (charts, garphs and etc) are the basic methods used in this type. Inferential: This type of statistic enables us to make generalization or prediction about population from a sample. The name implies, allow inference about a large population from a sampe It uses confirmatory methods 3/15/2016 Zakaria Khamis 7 On the last 3 Sunday , henry sold 2, 1 and 0 new car respectively Descriptive: Henry everage 1 new car sold for the last 3 sundays Inferential: Henry never sells more than 2 cars on Sunday Although the inferential statement is true for the last 3 Sunday we do not know if it is true for all Sunday 3/15/2016 Zakaria Khamis 8 Data • Is the collection of facts, they can be numbers, words, measurements or description of things • Data can be qualitatives or quantitatives • Qualitative data is a descriptive information, they based on observable quality but not measurable; example, of qualitative data are marital status, gender, job title and etc. • Quantitative data is a numerical information, they are expressed by means of numbers. This include all data which we can take their measurement; example, the height of objects, land elevation, temperature, rainfall, number of residence and etc . • Quantitative data can be discrete or continous Disrete data • This data can only take certain value (like the whole numbers) • No possiblity of values between the adjacent data values; example number of birth, number of death, number of students . • This include the data which we can count rather than take their measurement, therefore they cannot be expressed in decimal form. Continuous data • These are the data which can take any values (fractions, whole number or decimal). • There is a great possibility of values between adjacent values number. For instance, if we record the time taken and distance covered by a motor cycle travel from one station to another; we can have 122km/122.6km covered and 2hrs and 30min or 4hrs. • Example of Continous data: height, temperature,presure, distance, areas, time and etc. • Grouped v/s individual data Assignment • Attribute data can be categorized into 4 – Nominal – Ordinal – Interval – Ratio Nominal These are variables that provide descriptive information about an object. These are the observations that have been placed into a set of mutually exclusive and collectively exhaustive categories They do not imply order, size, or quantitative information E.g. city name, vegetation type code etc Ordinal The values of these variable imply rank. An ordinal attribute may be descriptive such as small, medium or large. They may be numeric. However, the number represent only order and not magnitude, for we assume no linearity between the values. It is possible to say that one observation is greater than another; however, we cannot say by how much the observation is greater than another E.g. Soil erosion can be ranked 1 to 10 classes. Each class show the order. 3/15/2016 Zakaria Khamis 13 Interval Are spread along a regularly spaced scale of measurement units. Equal changes in interval involve equal changes in the object being measured. In this scale zero is not meaningful No absolute zero, and consequently ratio interpretations are not possible E.g. Temperature data which is not in Kelvin 440C is 12 degree warmer than 320C But 440C is not twice as warm as 220C Ratio These are also interval; however they contain an additional property that the measurements are related to a meaningful zero point. They always have meaningful zero absolute zero. E.g. Rainfall data – zero rain means no rain and 2inchs rain is twice as 1inch rain. Temperature measured in Kelvin 1000K is twice as warm as 500K Population data etc. 3/15/2016 Zakaria Khamis 15 Sources of data • • • • Government and non government agencies Religious agencies Population Physical environment Primary souces Is the one in which the person or organization is responsible for data collection also uses and/ analysis. Interview, questionnaire, focus group discussion, surveying, photographing are some of the methods used (collection). Secondary sources It implies that the person or organization that is currently using or analyzing the data was not involved in their collection. That is to say it comprises second hand reports that contained data which have been condensed or summarizes or statistically manipulated or modified from primary or secondary sources. Examples of secondary sources • Books, such as biographies (not an autobiography), textbooks, Encyclopedias, dictionaries, handbooks • Articles, such as literature reviews, commentaries, research articles in all subject disciplines • Criticism of works of literature, art and music Spatial data It is also known as coordinate/geometric data – define the location and shape of the feature. The coordinate most often consists of a pair of numbers that specify location in relation to an origin. Spatial data most often use a Cartesian Coordinate System. However, it can also use Spherical Coordinate System. Spatial data can be discrete feature or Continuous feature Discrete feature may include – lake, building, well etc. Continuous feature may include – elevation, temperature, precipitation etc.