STATISTICS: Overview
Definition:
Statistics is
a branch of applied mathematics concerned with the scientific methods of
collecting, organizing, summarizing, presenting and analyzing data as well as
drawing valid conclusion and making reasonable decisions on the basis of such
analysis.
Division of
Statistics:
1. Descriptive statistics – comprises
those methods concerned with collecting and describing a set of data so as to
yield meaningful information.
2. Inferential statistics – comprises
those methods concerned with analysis of a set of data leading to predictions
or inferences about the set of data.
Basic
Terminologies:
1. Data – these are raw facts about
something.
2. Information – these are processed data
about something.
3. Population – it is the totality of all
actual or conceivable objects of a certain class under consideration.
4. Sample – is a finite number of objects
selected from population.
a.
TYPES
OF SAMPLING
i.
Simple
random sampling (Lottery Method) – the items are picked out for sample at
random.
ii.
Stratified
sampling – this procedure divides the population into subgroups or strata.
iii.
Systematic
sampling – the items are chosen from the population at uniform intervals of
time, space or order of occurrence.
5. Variables – a characteristic or
phenomena which may take on different values.
a.
TYPES
OF VARIABLES
i.
Qualitative
variables – these are variables which can be categorized according to the
characteristics that they possess.
-
e.g: gender; color; religion; student year
level; occupation; birthdates; zip codes; telephone numbers.
ii.
Quantitative
variables – these are variables which can be measured or counted.
-
e.g: age; monthly income; size of the family;
height; weight.
-
TYPES OF
QUANTITATIVE VARIABLES
a.
Discrete/
Discontinuous – these are variables which can be obtained by counting.
·
e.g.: # of students; # of books
b.
Continuous
– these are variables which can be obtained through the process of measurement.
·
e.g.: height; weight
Collection and Presentation of Data
Sources
of data
- Primary
data-
these are data coming from the primary sources or individuals who carry
original data relevant to a given problem.
- Secondary
data- these are data obtained from
published/unpublished reports compiled from original source.
Data
collection procedures
- Interview
Method- a person to person encounter
between the one soliciting information (interviewer) and one supplying the
data (interviewee).
- Questionnaire
method- it utilizes questions to obtain information,
but it is not necessary to have a person to person encounter like
interview.
- Observation
method- this method is use to obtain
data pertaining to behaviors of an individual at a time of occurrence of a
given situation.
- The
use of documents- it makes use of existing records
from both private and public agencies provides economical not only in
terms of cost but also in time and effort.
- Method
of experimentation- data that can be obtained
through a series of test/experiments may undergo in this method.
Methods
of Presentation
- Textual/
paragraph form- it presents data that are purely
qualitative or when very few numbers are involved.
- Tabular
a.
Parts
of Table
i.
table heading
ii.
body
a. stubs b. box head
iii.
footnote/ source note
- Graphical
or pictorial
a.
Types
of graph
i.
Line graph – an effective device to portray changes in
values with respect to time.
ii.
Bar graph – it can show categorical as well as chronological
comparison of data/variables.
iii.
Histogram – it is a graph showing data by using vertical
bars of various heights to represent frequencies of continuous data.
iv.
Pie graph – it is particularly appropriate for portraying
the relative magnitudes of the component parts of a whole.
v.
Pictograph – it employs pictures or symbols which are
normally drawn of the same size and in rows.
vi.
Statistical map – these are used to present quantitative
data which describes/classify geographical areas.
Examples of the different methods of Presentation
Textual
Table
Table 1.1
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Frequency Distribution
of STI College Bacoor Students by Program*
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(AY 2010 - 2011, 2nd
Semester)
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PROGRAMS
|
No. of Students
|
Percentage
|
||
BSCS
|
67
|
7.32%
|
||
BSIT
|
208
|
22.73%
|
||
BSBM/BSBA
|
126
|
13.77%
|
||
ACT
|
354
|
38.69%
|
||
DIT
|
108
|
11.80%
|
||
DCET
|
52
|
5.68%
|
||
TOTAL
|
915
|
100%
|
||
*Program often refer to the course a student is enrolled
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SOURCE: STI College Bacoor Registrar
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Line
Graph
Bar
Graph
Pie Graph
Histogram
Pictograph
