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Engineering Data
Analysis
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PRELIM TOPICS
1. OBTAINING DATA
1.1 Methods of Data Collection
1.2 Planning and Conducting
Surveys
1.3. Introduction to Design
Experiments
2. PROBABILITY
2.1 Relationship among Events
2.2 Rules of Probability
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PRELIM TOPICS
3. Discrete Probability Distribution
3.1 Random Variables
3.2 Cumulative Distribution
3.3 Binomial Distribution
3.4 Poisson Distribution
4. Continuous Probability
Distribution
4.1 Continuous Random Variables
4.2 Normal and Exponential
Distribution
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METHODS OF DATA
COLLECTION
Data collection is the process of gathering and measuring
information on variables of interest, in an established
systematic fashion that enables one to answer stated research
questions, test hypotheses, and evaluate outcomes.
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TYPES OF DATA
1. PRIMARY DATA
data which are collected a fresh
and for the first time and thus
happen to be original in
character and known as PRIMARY
DATA.
2. SECONDARY DATA
data which have been collected by
someone else and which have already
been passed through the statistical
process.
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METHODS OF DATA COLLECTION:
PRIMARY DATA
1. Observation
2. Interview
3. Questionnaire
4. Case Study
5. Survey
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METHODS OF DATA COLLECTION: PRIMARY DATA
OBSERVATION
Observation method
is a method
under which data from the field is
collected with the help of observation by
the observer or by personally going to the
field.
ADVANTAGES
DISADVANTAGES
Subjective bias
eliminated
Time consuming
Current information
Limited information
Independent to
respondent’s variable
Unforeseen factors
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TYPES OF OBSERVATION
STRUCTURED and UNSTRUCTURED
1. Structured Observation
when observation is done by characterizing style of
recording the observed information, standardized
conditions of observation , definition of the units to
be observed , selection of pertinent data of
observation.
Example: An auditor performing inventory analysis in store
2. Unstructured Observation
when observation is done without any thought
before observation.
Example: Observing children playing with new toys.
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TYPES OF OBSERVATION
PARTICIPANT and NON-PARTICIPANT
1. Participant
when the Observer is member of the group which
he is observing.
Advantages: 1. Observation of natural behavior
2. Closeness with the group
3. Better understanding
2. Non-participant
when observer is observing people without giving
any information to them.
Advantages: 1. Objectivity and neutrality
2. More willingness of the respondent
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TYPES OF OBSERVATION
CONTROLLED and UNCONTROLLED
1. Controlled
when the observation takes place in natural
condition. It is done to get spontaneous picture of
life and persons.
2. Uncontrolled
when observation takes place according to
definite pre arranged plans , with experimental
procedure then it is controlled observation
generally done in laboratory under controlled
condition.
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METHODS OF DATA COLLECTION: PRIMARY DATA
INTERVIEW METHOD
INTERVIEW METHOD
This method of collecting data
involves presentation or oralverbal stimuli and reply in
terms of oral-verbal responses.
Interview Method is an oral verbal communication
where interviewer asks questions (which are aimed
to get information required for study) to
respondent.
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TYPES OF INTERVIEW
• Personal interviews : The interviewer asks
questions generally in a face to face contact to
the other person or persons.
• Structured interviews : in this case, a set of predecided questions are there.
• Unstructured interviews : in this case, we don’t
follow a system of pre-determined questions.
• Focused interviews : attention is focused on the
given experience of the respondent and its possible
effects.
• Clinical interviews : concerned with broad
underlying feelings or motivations or with the course
of individual’s life experience, rather than with the
effects of the specific experience, as in the case of
focused interview.
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TYPES OF INTERVIEW
• Group interviews : a group of 6 to 8 individuals is
interviewed.
• Qualitative and quantitative interviews : divided
on the basis of subject matter i.e. whether
qualitative or quantitative.
• Individual interviews : interviewer meets a single
person and interviews him.
• Selection interviews : done for the selection of
people for certain jobs.
• Depth interviews : it deliberately aims to elicit
unconscious as well as other types of material
relating especially to personality dynamics and
motivations.
• Telephonic interviews : contacting samples on
telephone.
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METHODS OF DATA COLLECTION: PRIMARY DATA
QUESTIONNAIRE METHOD
QUESTIONNAIRE METHOD
This method of data collection is
quite popular, particularly in
case of big enquiries.
The questionnaire is mailed to respondents who are
expected to read and understand the questions
and write down the reply in the space meant for
the purpose in the questionnaire itsel f . Th e
respondents have to answer the questions on their
own.
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METHODS OF DATA COLLECTION: PRIMARY DATA
QUESTIONNAIRE METHOD
ADVANTAGES
DISADVANTAGES
Low cost even if the
geographical area is too large
Low rate of return of duly filled
questionnaire.
Answers are in respondents word
so free from bias.
Slowest method of data
collection.
Adequate time to think for
answers.
Difficult to know if the expected
respondent have filled the form
or it is filled by someone else.
Non approachable respondents
may be conveniently contacted.
Large samples can be used so
results are more reliable.
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METHODS OF DATA COLLECTION: PRIMARY DATA
CASE STUDY METHOD
CASE STUDY METHOD is essentially
an intensive investigation of the
particular unit under
consideration.
ADVANTAGES
They are less costly and less
time-consuming; they are
advantageous when exposure
data is expensive or hard to
obtain.
DISADVANTAGES
They are subject to selection
bias
They are advantageous when
They generally do not allow
studying dynamic populations in calculation of incidence
which follow-up is difficult.
(absolute risk).
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METHODS OF DATA COLLECTION: PRIMARY DATA
SURVEY METHOD
SURVEY METHOD is one of the
common methods of diagnosing
and solving of social problems is
that of undertaking surveys.
ADVANTAGES
DISADVANTAGES
Relatively easy to administer
Respondents may not feel
encouraged to provide
accurate, honest answers
Can be developed in less time
(compared to other datacollection methods)
Surveys with closed-ended
questions may have a lower
validity rate than other question
types.
Cost-effective, but cost
depends on survey mode
Data errors due to question nonresponses may exist.
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SECONDAY DATA:
SOURCES OF DATA
• Publications of Central, state , local
government
• Technical and trade journals
• Books, Magazines, Newspaper
• Reports & publications of industry ,bank, stock
exchange
• Reports by research scholars, Universities,
economist
• Public Records
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FACTORS TO BE CONSIDERED BEFORE USING
SECONDARY DATA
• Reliability of data – Who, when , which
methods, at what time etc.
• Suitability of data – Object ,scope, and
nature of original inquiry should be studied, as if
the study was with different objective then that
data is not suitable for current study
• Adequacy of data– Level of accuracy,
• Area differences then data is not adequate
for study
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SELECTION OF PROPER METHOD FOR
COLLECTION OF DATA
• Nature ,Scope and object of inquiry
• Availability of Funds
• Time Factor
• Precision Required
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DESIGNING A SURVEY
Surveys can take different forms. They can be used to
ask only one question or they can ask a series of
questions. We can use surveys to test out people’s
opinions or to test a hypothesis.
When designing a survey, the following steps are useful:
1. Determine the goal of your survey: What question do
you want to answer?
2. Identify the sample population: Whom will you
interview?
3. Choose an interviewing method: face-to-face
interview, phone interview, self-administered paper
survey, or internet survey.
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DESIGNING A SURVEY
4. Decide what questions you will ask in what order,
and how to phrase them. (This is important if there is
more than one piece of information you are
looking for.)
5. Conduct the interview and collect the
information.
6. Analyze the results by making graphs and
drawing conclusions.
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DESIGNING A SURVEY
Example:
1. Martha wants to construct a survey that shows
which sports students at her school like to play the
most.
Step 1: List the goal of the survey
Step 2: What population should she interview?
Step 3: How should she administer the survey?
Step 4: Create a data collection sheet that she
can use to record her results
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DESIGNING A SURVEY
Step 1: GOAL
The goal of the survey is to find the answer to the question:
“Which sports do students at Martha’s school like to play the
most?”
Step 2: POPULATION
A sample of the population would include a random sample
of the student population in Martha’s school. A good
strategy would be to randomly select students (using dice or
a random number generator) as they walk into an all-school
assembly.
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DESIGNING A SURVEY
Step 3: METHODS
Face-to-face interviews are a good choice in this case.
Interviews will be easy to conduct since the survey consists of
only one question which can be quickly answered and
recorded, and asking the question face to face will help
eliminate non-response bias.
Step 4: DATA
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DESIGNING A SURVEY
Example:
1. Juan wants to construct a survey that shows how
many hours per week the average student at his
school works.
Step 1: List the goal of the survey
Step 2: What population should she interview?
Step 3: How should she administer the survey?
Step 4: Create a data collection sheet that she
can use to record her results
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DESIGNING A SURVEY
Step 1: GOAL
The goal of the survey is to find the answer to the question
“How many hours per week do you work?”
Step 2: POPULATION
Juan suspects that older students might work more hours per
week than younger students. He decides that a stratified
sample of the student population would be appropriate in
this case. The strata are grade levels 9th through 12th. He
would need to find out what proportion of the students in his
school are in each grade level, and then include the same
proportions in his sample.
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DESIGNING A SURVEY
Step 3: METHODS
Face-to-face interviews are a good choice in this case since
the survey consists of two short questions which can be
quickly answered and recorded.
Step 4: DATA
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THE BASIS OF CONDUCTING AN
EXPERIMENT
1. With an experiment, the researcher is trying to learn
something new about the world, an explanation of 'why'
something happens.
2. The experiment must maintain internal and external
validity, or the results will be useless.
3. When designing an experiment, a researcher must
follow all of the steps of the scientific method, from
making sure that the hypothesis is valid and testable, to
using controls and statistical tests
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