introduction of statistics (complete file)

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Definition of Statistics
Observation and Variable
Types of Variables
Measurement Scales
Data collection
Sampling
1. Definition of Statistics:
• Science which enables us to draw conclusions about various phenomena on the basis
of real data collected on sample-basis.
• A tool for data-based research
• Quantitative Analysis
Latin words status (political state)
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Information useful to the state for example, information about the sizes of
population and armed forces.
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Numerical facts systematically arranged
For example statistics of prices, statistics of road accidents, statistics of crimes,
statistics of births, statistics of educational institutions, etc.
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A discipline that includes procedures and techniques used to collect process and
analyze numerical data to make inferences and to research decisions in the face of
uncertainty.
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Numerical quantities calculated from sample observations
CHARACTERISTICS OF THE SCIENCE OF STATISTICS
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Behaviour of aggregates or large groups of data
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Observations of the same kind not isolated
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Variability (exactly alike)
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Uncertainties (Probability)
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Characteristics or aspects of things which can be described numerically
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Subject to a number of random causes
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Statistical laws are valid on the average
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Statistical results might be misleading the incorrect if sufficient care in collecting,
processing and interpreting the data is not exercised or if the statistical data are
handled by a person who is not well versed in the subject mater of statistics.
THE WAY IN WHICH STATISTICS WORKS (FUNCTIONS)
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Statistics assists in summarizing the larger set of data in a form that is easily
understandable
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Efficient design of laboratory and field experiments as well as surveys
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A sound and effective planning in any field of inquiry
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In drawing general conclusions and in making predictions of how much of a thing
will happen under given conditions.
IMPORTANCE OF STATISTICS IN VARIOUS FIELDS
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A modern administrator whether in public or private sector
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A politician uses statistics advantageously to lend support
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A businessman, an industrial and a research worker all employ statistical methods in
their work. Banks, Insurance companies and Government all have their statistics
departments.
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Social scientist uses statistical methods in various areas
DATA: Results of observation
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Data are collected in many aspects of everyday life.
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Statements given to a police officer or physician or psychologist during an interview
are data.
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So are the correct and incorrect answers given by a student on a final examination.
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Almost any athletic event produces data.
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The time required by a runner to complete a marathon,
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The number of errors committed by a baseball team in nine innings of play.
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The spectral composition of light emitted by a star
OBSERVATIONS AND VARIABLES
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Observation often means any sort of numerical recording of information
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A characteristic that varies with an individual or an object is called a variable.
QUANTITATIVE AND QUALITATIVE VARIABLES
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A characteristic can be expressed numerically
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A qualitative characteristic is also called an attribute.
DISCRETE AND CONTINUOUS VARIABLES
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A discrete variable is one that can take only a discrete set of integers or whole numbers.
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A variable is called a continuous variable if it can take on any value-fractional or integral.
MEASUREMENT SCALES
By measurement, we usually mean the assigning of number to observations or objects and
scaling is a process of measuring.
NOMINAL SCALE
The classification or grouping of the observations into mutually exclusive qualitative categories
or classes is said to constitute a nominal scale.
ORDINAL OR RANKING SCALE
It includes the characteristic of a nominal scale and in addition has the property of ordering or
ranking of measurements.
INTERVAL SCALE
A measurement scale possessing a constant interval size (distance) but not a true zero point, is
called an interval scale.
RATIO SCALE
It is a special kind of an interval scale where the sale of measurement has a true zero point as its
origin. The ratio scale is used to measure weight, volume, distance, money, etc.
STEPS INVOLVED IN A STATISTICAL RESEARCH-PROJECT
Collection of Data:
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Primary Data
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Secondary Data
Sampling:
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Concept of Sampling
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Non-Random Versus Random Sampling
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Simple Random Sampling
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Other Types of Random Sampling
STEPS INVOLVED IN ANY STATISTICAL RESEARCH
Topic and significance of the study
Objective of your study
Methodology for data-collection
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Source of your data (COMPLETE enumeration), (PARTIAL enumeration)
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Sampling methodology
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Instrument for collecting data
COLLECTION OF PRIMARY DATA
One or more of the following methods are employed to collect primary data:
Direct Personal Investigation
Indirect Investigation
Collection through Questionnaires
Collection through Enumerators
Collection through Local Sources
Target population
How will we draw a sample from our population?
In order to draw a random sample from a finite population, the first thing that we need is the complete list of all the elements in
our population. This list is technically called the FRAME.
Sampled Population
NONRANDOM SAMPLING (QUOTA SAMPLING) non-lottery method
RANDOM SAMPLING (lottery method)
TYPES OF RANDOM SAMPLING
Simple Random Sampling
Stratified Random Sampling
Systematic Sampling
Cluster Sampling
Multi-stage Sampling, etc.
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