This document discusses the key differences between a pilot survey, sample survey, and census. It provides details about each: - A pilot survey is a small preliminary study to test aspects of a larger planned study, such as evaluating survey questions. - A sample survey collects data from a subset of a population to make inferences about the whole population. It is less expensive and faster than a census. - A census attempts to count every member of the entire population and collect data from all individuals. It provides a full count but is more expensive and time-consuming than a sample survey. The document also examines potential sources of error in surveys and censuses like sampling error, non-sampling error, and

1. Group Members:
AMIRA BINTI MISDAR
HATIKA BINTI MEGAT JAMIL
NUR ARINA BINTI NURUL ‘AKLA
NUR FATHANAH BINTI MOHAMAD ZAKI
Sept 2013 – Jan 2014
D2 CS 241 4A
2012738515
2012959065
2012918743
2012753899

2. QUESTION 1
DISTINGUISH CAREFULLY
BETWEEN A PILOT SURVEY, A
SAMPLE SURVEY AND A CENSUS.

3. Pilot Survey
A small experiment designed to test logistics and gather
information prior to a larger study, in order to improve the
latter’s quality and efficiency.
It also can reveal deficiencies in the design of a proposed
experiment or procedure and these can be addressed before
time and resources are expended on large scale studies.

4. Pilot Survey cont…
Reasons :
To test out the questions and see if they are
giving you the type of answers that you want.
People may not understand what you are
asking, so the reseacher may need to modify
questions to get what you want. If you do not
carry a pilot test and not work out on those
problems, the results from the final
questionnaire may be useless.

5. Use to obtain information about a large aggregate or population by
selecting and measuring a sample from that population.
Due to the variability of characteristics among items in the
population, researchers apply scientific sample designs in the
sample selection process to reduce the risk of a distorted view of
the population,
And then, they make inferences about the population based on the
information from the sample survey data.

6. COST
• A sample survey costs less than a
census because data are collected from
only part of a group.
TIME
• Results are obtained far more quickly
for a sample survey, than for a census.
Fewer units are contacted and less
data needs to be processed.
CONTROL
• The smaller scale of this operation
allows for better monitoring and
quality control.
• Fewer people have to respond in the
RESPONSE BURDEN sample.

7. • A census is a survey conducted on the full set of
observation objects belonging to a given
population or universe.
• The United Nations defines the essential
features of population and housing censuses as
"individual enumeration, universality within a
defined territory, simultaneity and defined
periodicity", and recommends that population
censuses be taken at least every 10 years.

8. Reasons:
Census data
are
published in
a wide
variety of
formats to be
accessible.
Data can be
represented
visually or
analyzed in
complex
statistical
models.
Census data offer a
unique insight into
small areas and
small demographic
groups.

9. WHY RESULTS FROM A CENSUS
MIGHT DIFFER FROM THE TRUE
VALUES IN THE POPULATION?

10. The accuracy of a survey estimate refers to the closeness
of the estimate to the true population value. Where there
is a discrepancy between the value of the survey estimate
and true population value, the difference between the
two is referred to as the error of the survey estimate.

11. Error (statistical error)
describes the difference
between a value obtained from
a data collection process and
the 'true' value for the
population.

12. Sampling error which arises
when only a part of the
population is used to
represent the whole
population.
It occurs solely as a result of
using a sample from a
population, rather than
conducting a census the
population.
It refers to the difference
between an estimate for a
population based on data from
a sample and the 'true' value for
that population which would
result if a census were taken.

13. POPULATION SPECIFICATION ERROR
•This error occurs when the researchers does not
understand who they should survey.
SAMPLE FRAME ERROR
•A frame error occurs when the wrong sub-population is
used to select a sample.
SELECTION ERROR
•This occurs when respondents self select their participation
in the study – only those that are interested respond.
Selection error can be controlled by going extra lengths to
get participation.

14. SAMPLING ERROR - These errors occur because of variation in
the number or representativeness of the sample that responds.
Sampling errors can be controlled by

15. • Caused by factors other than those related to
sample selection.
• Occur at any stage of a sample survey and can also
occur with censuses.
• It refers to the presence of any factor, whether
systemic or random.
• Results in the data values not accurately reflecting
the 'true' value for the population.

16. COVERAGE
ERROR
NONRESPONSE
ERROR
RESPONSE
ERROR
• Unit in the sample is incorrectly excluded or included, or
is duplicated in the sample.
• The failure to obtain a response from some unit
• because of absence, non-contact, refusal, or some other
reason.
• Respondents intentionally or accidentally providing
inaccurate responses.
• Concepts, questions or instructions are not clearly
understood by the respondent.

17. INTERVIEWER
ERROR
PROCESSING
ERROR
• Interviewers incorrectly record information; are not
neutral or objective; influence the respondent to answer
in a particular way; or assume responses based on
appearance or other characteristics.
• Errors that occur in the process of data collection, data
entry, coding, editing and output.

18. The greater the errors, the less reliable are
the results of the study
.
A credible data source will have measures in
place throughout the data collection process
to minimize the amount of error.
be transparent about the size of the
expected error so that users can decide
whether the data are 'fit for purpose'.

19. Two common measures of error:
Relative Standard
Error (RSE)
Standard Error (SE)
-

20. The standard error can be used to construct a
confidence interval.
• C.I is a range in which it is estimated
the true population value lies.
• C.I of different sizes can be created to
represent different levels of confidence
that the true population value will lie
within a particular range.

22. CALLBACKS
REWARD AND
INCENTIVES
DATA CHECKS
TRAINED
INTERVIEWERS
QUESTIONNAIRES
CONSTRUCTION

23. Example:
We want to conduct a survey about the
UiTM cafeteria in UiTM Machang. The
survey is based on the customers’
satisfaction on the food, price, facilities
and services provided by every cafeteria
in UiTM Machang. The customers’ are
selected from the all UiTM students in
that campus.

24. As for sampling error
happen because:
SAMPLE
FRAME
SELECTION

25. As for non-sampling
error happen
because:
COVERAGE ERROR
NON-RESPONSE ERROR
May happen due to unit in
the sample is incorrectly
excluded or included or is
duplicate in the sample.
Some of the respondents
might not respond or not
answers the questions being
asked.
RESPONSE ERROR
Respondents not
understand about the survey
or question that being asked.
PROCESSING ERROR
Occur in the process of data
collection, data
entry, coding, editing and
output.

26. REFERENCES
 http://www.statcan.gc.ca/edu/power-pouvoir/ch6/sampling-echantillonage/5214807eng.htm
 http://www.qualtrics.com/blog/frequent-sampling-errors/
 http://www.abs.gov.au/websitedbs/a3121120.nsf/home/statistical+language++types+of+error
 http://www.nss.gov.au/nss/home.nsf/NSS/4354A8928428F834CA2571AB002479CE?op
endocument
 http://srmo.sagepub.com/view/using-published-data/n1.xml
 http://stats.oecd.org/glossary/detail.asp?ID=3787
 http://support.sas.com/rnd/app/da/new/dasurvey.html

http://stats.oecd.org/glossary/detail.asp?ID=301