3. When was it collected? For how long?
May be out of date for what you want to analyze.
May not have been collected long enough for detecting
trends.
E.g. Milk marketshare in Vietnam in 2010
Is the data set complete?
There may be missing information on some
observations
Unless such missing information is caught and
corrected for, analysis will be biased.
SECONDARY DATA
4. It will save you time & money
It may be very accurate:
When especially a government agency has collected
the data, incredible amounts of time and money went
into it. It’s probably highly accurate.
It has great exploratory value:
Exploring research questions and formulating
hypothesis to test.
SECONDARY DATA
6. Do you have the time and money for:
Designing your collection instrument?
Selecting your population or sample?
Pretesting/the instrument to work out sources of bias?
Administration of the instrument?
Entry/collation of data?
Researcher error
Sample bias
Other confounding factors
PRIMARY DATA
7. What you must ask yourself:
Will the data answer my research question?
To answer that
You much first decide what your research question is
Then you need to decide what data/variables are
needed to scientifically answer the question
If that data exist in secondary form, then use
them to the extent you can, keeping in mind
limitations
But if it does not, and you are able to fund
primary collection, then it is the method of choice
PRIMARY DATA
8. Focus on 4 main methods:
Experiments
Telephone surveys
Written questionaires and surveys
Direct observation and personal interview
PRIMARY DATA
9. Experiment: a process that produces a single outcome
whose result cannot be predicted with certainty
Experimental design: a plan for performing an
experiment in which the variable of interest is defined.
One or more factors are manipulated so that the
impact on the variable of interest can be observed
Ex: Relationship between price and revenue
EXPERIMENT
10. Inexpensive
Short
Closed-End question: question that require
respondent to select from a short list of defined
choice
Demographic question: question relating to the
respondent charateristics, backgrounds and
attribute
TELEPHONE SURVEY
11. Define the issue
Define population
of interest
Develop survey
questions
Pretest the
survey
Determine
sample size &
method
Select sample &
call
Do customers accept an increase of
Viettel Internet price?
All of Viettel currrent customers
Explain purpose of price increase
Demographic: age, income, residential
Can you afford a price increase of service?
How much increase is acceptable?
Try on some customers. Check length,
clarity and easy. Modify if necessary
How much precise do you want?
How much variation is accepted?
Do not lead respondent
Record responses
12. Least expensive
More involved than telephone – more time to
complete
Open-End question: question that allow
respondent the freedom to respond with any
value, words or statements
WRITTEN QUESTIONAIRE & SURVEY
13. Define the issue
Define population
of interest
Design survey
instrument
Pretest the
survey
Determine
sample size &
method
Select sample &
send surveys
Do customers accept an increase of
Viettel Internet price?
All of Viettel currrent customers
Explain purpose of price increase
Ask important questions first. Provide specific
response option if you can
Layout: clear & attractive. Provide location
Demographic: age, income, residential
Try on some customers. Check length,
clarity and easy. Modify if necessary
How much precise do you want?
How much variation is accepted?
Do not lead respondent
Record responses
14. Ex: Do you agree with many other young people that
Facebook is beneficial?
=> In your opinion, is Facebook beneficial or waste of
time?
Ex: Would you like to pay a little extra on price to
support poor children to go to school?
=> Should product’s price be increased to contribute to
social welfare?
LEADING QUESTIONS
15. Ex: How much money do you make at your current job?
=> Which of the following categories reflect your monthly
income?
A. <$500 B. $500-$1,000 C. >$1,000
Ex: Rate from 1 to 10 on new product’s quality and service?
=> Rate new product’s quality 1 to 10 with 1 being the best.
Rate its service using the same 1 to 10 scale
______ Quality _______ Service
POORLY WORDED QUESTIONS
16. Ex: Do you approve or disapprove of the steps the Central
Bank have taken to deal with real estate crisis?
Ex: Do you think the Central Bank should lend businesses
money to finish housing building?
Ex: Do you think the Central Bank should expand credit
loan to citizens to buy houses?
The way the question is worded will affect the response!!
POORLY WORDED QUESTIONS
17. Physically observed what takes place in the process
Ex: How women differ from men in shopping at BigC?
Cost time & money
Subjective to different observers
Structured interview: interview in which questions are
scripted
Unstructured interview: interview that begin with one or
more broadly stated questions, with further questions being
based on the responses
DIRECT OBSERVATION & PERSONAL
INTERVIEW
18. Bias: effect that alters statistical result by systematically
dostorting it; different from a random error which may
distort on any occasion but balance out on average
Nonresponse bias: people who do not respond may
provide quite different data. Responses are heavily
weighted by people who feel strongly one way
Selection bias: subjects selected for data are subjective
Observer bias: people view the same event differently
DATA COLLECTION ISSUES
19. Measurement error
Internal validity: data are collected in such a way to
eliminate effects of variables that are not of researcher’s
interest
External validity: experiment results can be generalized
Pose question for potential bias and determine how to
reduce its effects
DATA COLLECTION ISSUES
