What is Statistics?
Statistics is the science of analyzing and interpreting information. Such information is referred to as data.
Types of Data:
There are two major categories of data: primary and secondary data.
Primary Data: This is new data obtained from experiments, surveys, questionnaires, and investigations carried out by an individual or organization to be used for a certain purpose.
Secondary Data: This is existing data that is made available for use such as Annual Abstract of Statistics, Research Agencies, Publications, Internets, etc.
Recall that data is made up of a collection of variables, however a variable can either be qualitative or quantitative.
Quantitative Data: This refers to an analysis of numerical values such as shoe size or mass, this is further sub-divided into discrete and continuous data.
Discrete Data: These are data obtained by counting, they can only take on certain values – usually whole numbers or half numbers e.g. 20 cars, 80 houses, 10men. Note that shoe sizes may be 8, 8½, 9, 9½, etc. however it is impossible to have 8\( \frac{1}{5}\) shoe size or 10.5 men, 20.2 Cars, etc.
Continuous Data: These are measurable data that can take on any values within a specified range. Their accuracy depends on the accuracy of the measuring device e.g. the temperature of patients can be 35.5º, 36º, 36.4º, etc. the accuracy of these readings depends on the accuracy of the thermometer used. Other examples of continuous data are height, mass, volume, etc.
Qualitative Data: This refers to data that take on non-numerical values which can be described in words such as the quality of colour, taste, brightness, modes of transport, make of car, etc.
Raw Data: Data that is freshly collected and not yet analysed are said to be raw data.
Organized Data- Frequency table: This refers to data presentation in a frequency distribution i.e. usually arranged in ascending order with corresponding frequencies.
Graphical Presentation of Data:
When data is presented in diagrammatical or pictorial forms, such data presentation is easier to understand than tables. For example, newspapers and televisions use graphs and diagrams to present data. The most commonly used diagrams are discussed in this lesson.
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