CHAPTER 1: DESCRIPTIVE STATISTICS
1.1 Introduction
Statistics is concerned with the scientific method by which information is collected,
organised, analysed and interpreted for the purpose of description and decision making.
Examples using statistics are: Hang Seng Index, Life or car insurance rate, Unemployment
rate, Consumer Price Index, etc.
There are two subdivisions of statistical method.
(a) Descriptive Statistics - It deals with the presentation of numerical facts, or data, in
either tables or graphs form, and with the methodology of analysing the data.
(b) Inferential Statistics - It involves techniques for making inferences about the whole
population on the basis of observations obtained from samples.
1.2 Some Basic Definitions
(a) Population - A population is the group from which data are to be collected.
(b) Sample - A sample is a subset of a population.
(c) Variable - A variable is a feature characteristic of any member of a population
differing in quality or quantity from one member to another.
(d) Quantitative variable - A variable differing in quantity is called quantitative variable,
for example, the weight of a person, number of people in a
car.
(e) Qualitative variable - A variable differing in quality is called a qualitative variable or
attribute, for example, color, the degree of damage of a car in
an accident.
(f) Discrete variable - A discrete variable is one which no value may be assumed
between two given values, for example, number of children in a
family.
(h) Continuous variable - A continuous variable is one which any value may be assumed
between two given values, for example, the time for 100-meter
run.
1.3 Method of Data Collection
Statistics very often involves the collection of data. There are many ways to obtain data, and
the World Wide Web is one of them. The advantages and disadvantages of common data
collecting method are discussed below.
1.3.1 Postal Questionnaire
The...