Surveys can measure population characteristics, behaviors, attitudes, and needs through self-reported or observed data collection methods. Common methods include mobile surveys, online surveys, telephone surveys, mail surveys, and face-to-face surveys. Each method has advantages and disadvantages related to costs, response rates, and potential biases. Proper planning, sampling, questionnaire design, data collection, and analysis are needed to minimize errors and biases.

1. Surveys provide a means of measuring a population’s characteristics, self-reported and observed
behaviour, awareness of programs, attitudes or opinions, and needs.
Mode of data Collection for the survey research mostly based on the two type they are Self-completion
surveys, Interviewer-based surveys, Combinations of collection methods so on .,
1. Mobile survey
2. Online Survey
3. Telephone
4. Mail
5. Face to Face
1. Mobile survey
Mobile data collection or mobile surveys is an increasingly popular method of data collection. Over 50% of
surveys today are opened on mobile devices. The survey form, app or collection tool is on a mobile device
such as a smart phone or a tablet. These devices offer innovative ways to gather data, and eliminate the
laborious "data entry" which delays data analysis and understanding. By eliminating paper,
Mobile data collection can also dramatically reduce costs: one of the example is World Bank study in
Guatemala found a 71% decrease in cost while using mobile data collection, compared to the previous
paper-based approach.
SMS surveys are a suitable mobile survey data collection channel for many situations that require fast, high
volume responses. As a result, SMS surveys can deliver 80% of responses in less than 2 hours and often at
much lower cost compared to face-to-face surveys, due to the elimination of travel/personnel costs. The
response times and the possibility to reach previously hard-to-reach target groups.
2. Online survey
Online surveys or internet survey are becoming an essential research tool for a variety of research fields,
which is used for so many official statistics research. Web surveys are faster, simpler, and
cheaper. However, lower costs are not so straightforward in practice, as they are strongly interconnected to
errors. Because response rate comparisons to other survey modes are usually not favourable for online
surveys, efforts to achieve a higher response rate may substantially increase costs
 The entire data collection period is significantly shortened, as all data can be collected and processed for
the futher uses. Interaction between the respondent and the questionnaire is more dynamic compared to e-
mail or paper surveys
 Pop-up instructions can be provided for individual questions to provide help with questions exactly where
assistance is required
 Questions with long lists of answer choices can be used to provide immediate coding of answers to certain
questions that are usually asked in an open-ended fashion in paper questionnaires
 Online surveys can be tailored to the situation .Online questionnaires may be improved by applying
usability testing, where usability is measured with reference to the speed with which a task can be
performed, the frequency of errors and user satisfaction with the interface.
Key methodological issues of online surveys
 Sampling: The difference between probability samples and non-probability samples is crucial. Probability
samples are highly affected by problems of non-coverage and frame problems. Because coverage and frame
problems can significantly impact data quality, they should be adequately reported when disseminating the
research results.
 Invitations: Due to the lack of sampling frames many online survey invitations are published in the form
of an URL link on web sites or in other media, which leads to sample selection bias that is out of research
control and to non-probability samples.
 Non-response: Several other non-response patterns can be observed in online surveys,Non-bias responses
could be questioned in this type of situation. The most concrete way to gain feedback is to publicize what is
done with the results. To take concrete actions based on feedback.
 Questionnaire design: Appropriate questionnaire design can help lowering the measurement error that can
arise also due to the respondents or the survey mode itself.

2.  Post-survey adjustments: Post-survey adjustment is need from probability selection, when the research
face non-coverage and non-response problems. The standard statistical inference procedures still require a
probability sample
3. Telephone survey
A telephone survey is one of the survey methods used in collecting data either fromthe general population
or from a specific target population. Telephone numbers are utilized by trained interviewers to contact and
gather information from possible respondents
 Use of interviewers encourages sample persons to respond, leading to higher response rates.
 Interviewers can increase comprehension of questions by answering respondents' questions.
 Fairly cost efficient, depending on local call charge structure.
 Good for large national sampling frames.
 Some potential for interviewer bias Cannot be used for non-audio information (graphics, demonstrations,
taste/smell samples)
 Three types:
 Traditional telephone interviews
 Computer assisted telephone dialing
 Computer assisted telephone interviewing (CATI)
4. Mail survey
The questionnaire may be handed to the respondents or mailed to them, but in all cases they are returned to the
researcher via mail.
 The cost survey compare to other is very low, since bulk postage is cheap in most countries
 Long delays, often several months, before the surveys are returned and statistical analysis can begin
 Not suitable for issues that may require clarification
 Respondents can answer at their own
 No interviewer bias
 Large amount of information can be obtained: some mail surveys are as long as 50 pages
 Response rates can be improved by using mail panels, monetary incentives.
 Face-to-Face
Suitable for locations where telephone or mail are not developed
 Potential for interviewer bias
 Easy to manipulate by completing multiple times to skew results
5. Mixed-mode surveys
Researchers can combine several above methods for the data collection. For example, researchers can invite
shoppers at malls, and send willing participants questionnaires by emails. With the introduction of computers to
the survey process, survey mode now includes combinations of different approaches or mixed-mode designs.
Some of the most common methods are:[18]
 Computer-assisted personal interviewing (CAPI): The computer displays the questions on screen, the
interviewer reads them to the respondent, and then enters the respondent's answers.
 Audio computer-assisted self-interviewing (audio CASI): The respondent operates the computer, the
computer displays the question on the screen and plays recordings of the questions to the respondents, who
then enters his/her answers.
 Computer-assisted telephone interviewing (CATI)
 Interactive voice response (IVR): The computer plays recordings of the questions to respondents over the
telephone, who then respond by using the keypad of the telephone or speaking their answers aloud.
All other errors associated with collecting survey data are called non-sampling errors. Although they cannot be
measured in the same way as sampling errors, they are just as important.

3. The following table lists common sources of non-sampling error while collecting the data research sources and
some strategies to minimise them.
Source of error Examples Strategies to minimise error
Planning and
interpretation
Inadequate definitions of
concepts, terms or populations.
Ensure all concepts, terms and populations are defined
precisely through consultation between data users and
survey designers.
Sample selection Inadequate list from which
sample is selected; biased sample
selection.
Check list for accuracy, duplicates and missing units; use
appropriate selection procedures (see “Bias and
Accuracy” below).
Survey methods Inappropriate method (e.g., mail
survey for a very complicated
topic).
Choose an appropriate method and test thoroughly.
Questionnaire Loaded, misleading or ambiguous
questions, poor layout or
sequencing.
Use plain English, clear questions and logical layout; test
thoroughly.
Interviewers Leading respondents, making
assumptions, misunderstanding
or misrecording answers.
Provide clear interviewer instructions and appropriate
training, including exercises and field supervision.
Respondents Refusals, memory problems,
rounding answers, protecting
personal interests or integrity.
Promote survey through public media; ensure
confidentiality; if interviewer-based, use well-trained,
impartial interviewers and probing techniques; if mail-
based, use a well-written introductory letter.
Processing Errors in data entry, coding or
editing.
Adequately train and supervise processing staff; check a
sample of each person’s work.
Estimation Incorrect weighting, errors in
calculation of estimates.
Ensure that skilled statisticians undertake estimation.