an introduction to the basic terms of statistics

1. Introduction to
Statistics
Chapter 1
Instructor: Ms Abeera Ilyas

2. Meaning of Statistics
• Latin word – “Status” meaning a political state originally
meant information useful to state
• Population size
• Number of educational institutes etc
• By definition – “numerical facts systematically arranged”, a
commonly known synonym-data
• “A discipline that includes procedures and techniques used to
collect, process and analyze numerical data to make
inferences and to reach decision in face of uncertainty.
• “the word statistics are numerical quantities calculated from
sample observations; a single quantity that has so been
calculated is called a statistic.”

3. Characteristics of Statistics
• It deals with the behavior of aggregate or large groups of data.
• It deals with aggregate of observations of same kind rather
than isolated figures.
• It deals with variability that obscure underlying patterns. No
two objects in this universe are exactly alike otherwise no
statistics.
• It deals with uncertainties as every process of getting
observations whether controlled or uncontrolled, involves
deficiencies or chance variation.
• Statistics deals with those characteristics or aspects of things
which can be described numerically either by counts or by
measurements.

4. Characteristics of Statistics
• It deals with those aggregates which are subject to random
causes e.g height is subject to a number of causes like race,
ancestry, age, diet, climate etc.
• Statistical laws are valid on the average or in the long run.
Inferences are therefore made in the face of uncertainty.
• Statistical results might be misleading and incorrect if
sufficient care in collecting, processing and interpreting data is
not exercised.

5. Descriptive and Inferential
Statistics
• Descriptive Statistics:
• The branch of statistics which deals with concepts and methods
concerned with summarization and description of the important
aspects of numerical data. It also deals with condensation,
graphical displays and computation of numerical quantities that
provide information about center of data (meta deta).
• Inferential Statistics:
• It deals with the procedures about the characteristics that
describe larger group of data, called population, from the
knowledge derived from only a part of data, called sample. It also
includes estimation of population and testing of hypotheses. It is
mostly based on probability theory.

6. Importance of Statistics
• It assists in summarizing the larger sets of data in an
understandable form.
• It is helpful in the efficient design of laboratory, field
experiments and surveys.
• It is important for the sound and effective planning in any field
of inquiry
• It draws general conclusions in making predictions eg how
much of a thing will happen in given circumstances.
• Statistical tools are powerful for analyzing numerical data and
used in every branch of learning.
• It helps the administrators to draw factual basis for a decision
from statistical data.

7. Collection of Data
There are two methods for collection of data
• Census:
• Collection by complete enumeration of the whole field which
might be too costly.
• Sample:
• Partial enumeration associated with a sample or limited data, it
saves time and money both.
Data is classified in two types
• Primary data:
• Data has been originally collected (raw data) and not undergone
any sort of statistical treatment.
• Secondary data:
• Data has undergone statistical techniques at least once i-e
collection, classification, tabulation or presentation in some form.

8. Collection of Primary data
• Direct Personal Investigation:
• Collection of data is done personally by investigator from
individuals. The information collected is considered accurate and
complete since it has been collected personally. The method is
time consuming and costly but considered best for research
purposes because of minimal chance of error. Personal biasness is
involved.
• Indirect investigation:
• Third parties or witnesses having information are interviewed.
The method is useful when information is complex or there is
reluctance or indifference in part of informants. It can be adopted
for extensive inquiries. Chance of error is present from either the
witnesses or personal biasness.

9. Collection of Primary data
• Collection through Questionnaires:
• It is an inquiry form comprising of a number of pertinent
questions with space for entering information asked. Usually sent
by mail or delivered electronically and requested to respond in a
certain period of time. The method is cheap and good for
extensive inquiries. Fairly standard method for routine collection
of data but the chances of error is high since the performa might
be incomplete or not delivered back at all.
• Collection through enumerators:
• The information is gathered by employing trained enumerators
who assist informants in making the entries in the schedules or
questionnaires correctly. Most reliable if the enumerator is well
trained and experienced. Best for large scale governmental
inquiry. The process is very costly.

10. Collection of Primary data
• Collection through local resources:
• No formal collection of data but the agents or correspondents are
directed to collect and send the information using their own
judgments. Very cheap method but can only provide estimates.

11. Collection of Secondary data
• Official:
• Can be collected through the publications of the statistical
division, Ministry of finance, The federal and provincial bureaus
of Statistics etc
• Semi-Official:
• Information printed by semi-govt institutes eg SBP, Railway,
Central cotton committee, Boards of Economic inquiry, District
councils, municipalities etc.
• Publication of trade associations, Chamber of Commerce.
• Technical and trade journals and newspapers.
• Research organizations such as universities etc