THE IMPORTANCE OF STATISTICS IN GEOGRAPHY
- Statistics helps to draw relevant influence into geography using certain statistical data such as measures of central tendencies (mean, mode and median) and measures of dispersion (range variance and standard deviation)
- It helps to derive the essential information required in the field of geography
- Statistics in geography helps to reduce the volume of information and data to a manageable proportion
SAMPLING IN STATISTICAL GEOGRAPHY
MEANING: Sampling is a way choosing from a population certain individuals or items. In other words, it can be seen as the selection of a certain number of occurrence whose total number may be known or unknown.
When carrying out an investigation or research, the researcher may find out that at times it is not possible to examine every item with the relevant characteristics in this case, all he needs do is to examine a limited number of items and hope that he can obtain the information he requires about the universe. The group of items selected or chosen for the research is known as “sample” and the act of investigation or choosing the selected group is “sampling”
CHARACTERISTICS OF SMAPLING
- Any sample gives some information about the parent universe or population
- The larger the sample, the more accurate the estimation or inferences.
- The larger the sample, the higher the degree of stability
- As long as the sample is large enough to avoid the influence of anomalies, it will then be a representative of the population.
SAMPLING METHODS OR TECHNIQUES
The purpose of sampling is to obtain information about a particular characteristic of a parent population or universe and it is important to understand the information required. This will then decide the sampling method to be adopted. Sampling therefore can be carried out using the following methods.
- Random method
- Non-random method
A perfect sampling is one that exactly represents the population from which it is drawn. For example if 10% of the population has feature A. 10% of the population has feature A. if 80% of the population is ‘Y’, 80% of the population will be “Y”. If one sample is chosen is such a way that every item has equal chance of being chosen, then this sample will likely represent the population adequately.
One method of obtaining a sample by random is to assign numbers to each members of the population. Write these numbers on a small piece of paper, place them in a box and then draw the numbers from the box. Mix thoroughly before each draw. This method of sampling is called “random sampling”.
NON RANDOM SAMPLING TECHNIQUE
There are mainly four types of non-random sampling techniques.
- Haphazard Sampling: This is also called accidental sampling. It is an unscientific and unsystematic selection of events or items from the parent universe. Haphazard sampling, unlike the random sampling is not carried out according to rules.
- Availability Sampling: This type of non-random sampling is based on the availability of information such as the occurrence of general disease and activities of secret societies
- Judgment Sampling: This is a non-random sampling technique with the selection of items or events based on value judgment e.g. getting to know the history of a village, ne does not have to see a boy of fifteen years, instead, an elderly person has to be chosen or consulted.
- Quota Sampling: This is also non-scientific. It is essentially based on the selection of a quota of the population which is randomly chosen and so it is based.
WHAT IS A MAP?
A map can be defined or regarded essential as an integrated assembly or synthesis of four categories of information – Points, Lines, Areas and Names, which are presented in types, characters, patterns, symbols, sizes, thickness, form and line. But these have to be considered not in isolation but also in relation to each other so as to give maximum over-all clarity, legibility and usual impact.
One important concept of map-making and designing involves the presentation of information so as to create for the map maker a clear separation of the various distinctions to be shown on the map.
GENERAL FEATURES OF A MAP
Whenever a map or diagram is drawn by anybody, it is ideal in most cases to compile a preliminary draft. The student or cartographer has to consider the purpose of the map, the several materials from which it is to be constructed and the most striking and effective method to be used he then selects carefully the base outline, the scale and the size of the finished map.
- BASE-MAP: A base-map is an outline used for plotting information. It consists of the coastlines and frontiers or major administrative divisions and natural drainage patterns.
- MAP-CHECKING: All maps should be carefully checked upon completion. The checking should be systematic in terms of spelling, line work, shading, key, scale line as well as correct.
- SCALE: When compiling a map, the first essential thing is to determine the scale to be used. It is obviously necessary to take into consideration the extent of the ground to be depicted and available size of the material. The amount of details which should be included is clearly a function of the scale.
- FRAMES AND MARGINS: A map must have a margin or frame. Graphs and diagrams may or may have margins depending on their appearances. Margins or frames should be as simple as possible. A map with its key and legend should be complete in itself and self-explanatory.
CLASSIFICATION OF MAPS
Owning to so many types or classes of maps, it is important to classify them in order provide a better basis for the appreciation of their similarities and differences, hence, it is desirable to look at it from three perspectives, namely:
- Their scale
- Their communication objective
- Their subject matter and objectives
CLASSIFICATION OF MAPS ON THE BASIS OF THEIR SCALE
All maps are representation of reality.
The proportion or ratio between the map dimension and those of reality is called the map scale. On the basis of their scales, maps can be divided into three.
- Small – scale map
- Large – scale map
- Medium – scale map
- SMALL-SCALE MAP
These maps represent very larges areas such as the whole continent or the entire world. In this way, only a few details can be shown on the map. A city like Benin may appear only as a dot on a world map. Example of such small scale maps is 1:100,000 or 1:100,000,000. The atlas contains examples of small scale mapsl
- LARGE – SCALE MAP
Large scale maps represent small areas., such as school compounds or a city. It is therefore possible to show the position and arrangement of buildings in a school compound or streets in a city. Example of a large scale map: 1cm represent 10m.
- MEDIUM – SCLAE MAP
These maps are in between the small-scale maps and the larger scale maps:
CLASSIFICATION OF MAPS ON THE BASIS OF THEIR COUUMINICATION OBJECTIVES
The various geographical phenomena of the world that can represented on maps are almost infinite. On this basis therefore, maps can be classified as:
- General maps
- Thematic maps
General map are those in which the objective is to portray the spatial association of selection of geographical phenomena. Things like road, settlements, boundaries, water courses, heights of coastlines and bodies of water are typically portrayed on a general map.
Topographical maps are concerned mainly with the surface of the earth.
Thematic maps are quite different from general maps. General maps attempt to show the positional relationship of varieties of geographical phenomena on one map; while thematic maps concentrate on the spatial variation of a single phenomenon. Examples of thematic map are maps of average annual precipitation or temperature, population, atmospheric pressure, average annual income, grain production etc.
CLASSIFICATION OF MAPS ON THE BASIS OF THEIR SUBJECT MATTER AND FUNCTIONS
On the basis of their subject matter and functions, several forms of maps can be classified as follows:
- CADASTRAL MAPS: These are maps which record property boundaries. Their principal use is to provide basis on which to assess taxes.
- PLANS: These are details maps showing buildings, road ways, boundaries and administrative boundaries. They are also large scale maps, e.g. town plans
- CHARTS: These are maps designed to aid navigators. There are various kinds of charts such as those used by the mariners at sea called nautical charts and those used by the navigators of aircrafts called aero-nautical charts because they are used for plotting positions and establishing bearings in the air.
- ROAD MAPS: These are closely allied to charts in function. Travelers on land ordinarily do not need to plot positions and calculate courses as do navigators on the sea and air, but then, do need guide as to where roads leads to and, how distant some cities are. In some countries they are issued free. Road maps are really old but with the advent of automobiles, road maps and road atlases have become common. There is no limit to the number of classes of maps that can be created on the basis of this subject matter and function. Thus there are soil maps, geological maps, climatic maps, population maps, statistical map etc.
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