Measurement instrument refers to
various methods through which a researcher obtains data from respondents for
his research work. The term data refers to all forms of information that
researchers obtain from the participant of the study. Adedokun (2003:57)
asserts that data refers “to any fact, observation or facts relating to the
subject of the study”. There are different types of measurement instruments
that can be used by researchers for their studies; it depends on the nature of
research that is to be carried out. In this write up, we shall discuss various
measurement instruments that can be used alongside with studies that are
suitable for them.
However, the collection of data is an important part of any research activity.
This is because; the conclusions of the study are based on what the data
reveals. Hence, no researcher is greater than his data.  Basically, data
can be obtained from two major sources; primary and secondary sources. Primary
data represents the information gathered by the researcher through the use of
questionnaire or personal interview or observation method; while in secondary
data, the researcher collects information that has already been obtained and
processed by government departments or various agencies before it is made
available for other interested users. These are published and unpublished
sources e.g. journals, textbooks, newspapers, magazines, fliers, annual
reports, bulletins, periodicals etc As a result, the kind of data to be
collected, the method of collection to be used, and the scoring of the data
must be considered when undertaken any research activity. 
Types of Data to be Collected
According to Aina, 2004; Adedokun, 2003; Avwokeni, 2006; Adeniyi; Oyekanmi and
Tijani, 2011. Researchers can collect the following types of data from
  • Demographic information or data e.g. age, sex, gender,
    educational background, ethnicity, religion, etc
  • Test scores
  • Events
  • Responses to researchers questions in an interview or
    written replies to a survey question
  • Grade point averages obtainable from school records
  • Essay written by students e.g. projects, theses and
  • Anecdotal records kept by teachers or counselors or
In fact, the list of data to be
collected is not limited to the one listed above. For this reason, it is
important for every researcher to decide on what kind(s) of data he intends to
collect and by what method to collect it. Those methods that researchers use in
collecting his desired data are known as research or measurement instrument.
Data Collection Instruments
These are instruments that are used to collect data from participants of the
study. They are important for collecting data in all types of research methods.
They are mainly used by researchers to collect reliable data which will later
be analyzed (Aina, 2004). They include questionnaire, interviews, observations,
focus group discussion and experiment. Each of the instruments shall be
discussed in turn and also point out their merits and demerits.
  • Questionnaire
The questionnaire is the commonly
used instrument for collecting research data from the participants of a study.
“It basically seeks the opinions of individuals in a sample or a population on
issues directly related to the objectives of the research study” (Aina,
2004:348). The questionnaire consists of a set of structured and unstructured
questions designed by researchers to obtain data from the respondents. No
research is better than its questionnaire and a faulty questionnaire means
faulty research. Hence, a questionnaire designed must be valid, reliable and
must not be bogus so that the data collected can validate the research. Questionnaire
has many advantages which include anonymity of the respondents is guaranteed;
it facilitates the collection of large amounts of data in a relatively short
period and it is cheap to administer. The major demerit of the method is that
some confusing and misleading questions cannot be clarified as the researcher
may not be there to explain the questions, and also, sometimes, the questions
may not be easily comprehensible to individuals who are illiterate, thus, the
method is restricted only to educated respondents.
Moreover, the characteristics of a good questionnaire according to Popoola
(2011) consist of:
  • Questions should not be ambiguous. This implies that it
    must be capable of only one interpretation.
  • Questions must be easily understood.
  • Questions should be capable of having a precise answer.
  • Questions must not contain words of vague meaning.
  • Questions should not require rigorous calculations.
  • Questions should not require the respondent to decide
    upon classification.
  • Questions must not be in such a form that the answers
    will be biased.
  • The questionnaire should not be too long.
  • It should not be too wordy.
  • The questionnaire should cover the exact object of the
  • Interview
Interview is a measurement
instrument otherwise known as oral questionnaire. It involves a process where a
researcher solicits information from respondents through verbal interaction. A
researcher would have previously prepared a schedule list of structured
questions pertinent to the study before meeting respondents for their opinions
on a subject matter. The researcher poses questions to the respondents and the
answers are recorded by the researcher. Materials that could be used during
interview period include tape recorder, paper and biro. The major advantage of
this method is that it produces high response rate. Besides, it tends to be
representative of the entire population of the study, and personal contact
between the researcher and respondents enables the researcher to explain
confusing and ambiguous questions in detail (Aina, 2004; Popoola, 2011).
However, its disadvantages include interviewer’s bias; inaccessibility to
wealthy respondents due to fear of insecurity and the amount of data that can
be collected through this method is usually limited compare to questionnaire method.
Interview can be conducted personally or through telephone or electronic
mailing system.   
  • Observation
This is an instrument that is
employed by a researcher in which an individual behavior or situation is
observed and recorded. There are two types of observation: participant
observation and non-participant observation. In participant observation, the
researcher is a member of the group to be observed. Here, accurate and timely
result would be obtained by the researcher but it has the problem of biasness.
Non-participant observation on the other hand, the researcher is not a member
of the group to be observed. Here, the result will be viable as it is free from
being biased but it has the problem of inaccuracy and delayed result. Both
observation methods enhance first hand information, flexible and cheaper to
carryout, demand less active cooperation of the observed and their results are
reliable for research activity.
However, Akinade & Owolabi (2009) assert that observation method is popular
tool in research especially in behavioural and social sciences; the authors
argue that it requires special skills to make and assess behavioural
observation in research. In carrying out behavioural observation, first thing
to do is to develop behavioural categories (coding scheme). This involves
identifying specific attributes that will give clues to the problem at hand.
The authors further reiterated that researchers may observe the following
guidelines when developing observation method:
  • “Clearly define the goal of the instrument;
  • Carry out preliminary observations of your subjects
    under the conditions that will prevail in the course of the study with the
    aim of identifying behaviours exhibited by the subjects; and
  • Construct a complete list of the identified behavior.
    Also, behavioural categories can also be developed through literature
    search. These will provide opportunity to determine whether a similar
    study had previously been conducted. The result of such similar study may
    be adopted or adapted in the present study” (Akinade & Owolabi,
  • Focus Group Discussion:
This data collection instrument
refers to a process whereby researchers obtain data from large group of people
at the same time. This method is different from interview method; in an
interview method, researcher focuses on one person at a time but in a focus
group discussion method, the researcher obtains data from large number (group)
of people for his research activity. Focus group discussion method is very
popular when carrying out research in the field of behavioural science, library
and information science, archival science, records and information technology.
It could be noted here that a need may arise for a researcher to use more than
2 or 3 approaches to obtain data for his research activity. This depends on the
supervisor, nature of the research or problem to be investigated.
However, in focus group discussion; a researcher identifies key informants that
may be contacted to elicit the deserved information on the variable(s) of
interest in a study. It is very important to note that in evaluator study or
when accessing the performance of a system or a project or when working at a
policy and its impact on a particular operation in a society or organization;
focus group discussion method could employed. The approach is used to generate
qualitative data in explaining a phenomenon under study or investigation.
Membership of the focus group discussion should not exceed 10 members at a
time. It is like a mini conference where members of a group could be assembled
in a conducive location. Before now, it is needful for the researcher to have
obtained their consent to take part in the study.
Besides, the researcher must design a focus group discussion guide. The guide
must contain outlines that capture variables of interest in the study. For
example, in a study like: “Customers’ satisfaction with information services or
products of Babcock university library”. The following guidelines may be
prepared by the researcher:
  • Nature of the library services;
  • Nature of the products;
  • Level of satisfaction of the users;
  • Quality of the users, etc.
The following materials are needed
for this method of data collection:
  • Research assistants;
  • Video recorder and cassette;
  • Biro and paper;
  • Tape recorder and cassette, and
  • Light refreshment to entertain the participants.
After the focus group discussion
exercise, the researcher has to transcribe the data into qualitative
information e.g. on the nature of reference services available in the library; in
a group where 10 members are involved, if 7 members affirmed that they are
having good reference services in their library while the rest members’
response are negative. Then it can be calculated/quantify as: 7/10 *100 = 70%;
this is the figure that the researcher will report in his work. Moreover, the
major advantage of this method is that it added credibility and originality to
the research activity while it challenges include: too cost to carry out, it
takes too much of time to conduct and some of the respondents may not be free
to contribute extensively especially if their boss is invited to such
  • Experiment
This type of data collection
instrument takes place in pure and applied science research. Here the
researchers carry out some experiments in the laboratory setting in order to
test some reactions that may take place in the object of research. The
advantages of this method is that it produces immediate result, its results are
viable and error free if it is well carry out under normal condition/circumstances.
While, its problems include: it is too costly to undertake and those chemicals
used may cause permanent damage to the researcher if they are carelessly

Table1: Classification of Research Based on Data Collection Instruments

of Research
Collection Instruments
Interview and observation.
focus group discussion, interview and observation.
interview, focus group discussion and observation.
e.g. correlational research
questionnaire, focus group discussion and interview
focus group discussion and interview
group discussion, interview and observation
and observation
and interview
observation, focus group discussion, interview and experiment in case of
pure science research.
observation and interview.

It could be re-emphasized here that researchers are not restricted only to
different methods of data collection instruments and their classification as
presented in this paper but the choice of which method to apply depends on the
researcher, nature or problem to be investigated and prevailing circumstances
at the time of carrying out the study. Thus, researchers are free to use any
method they deem fit for their research.
Adedokun, J.A. (2003). Basics of Research Methodology. Sagamu: New Hope
Adeniyi, A.L.; Oyekanmi, A.O. & Tijani, M.O. (2011). Essentials of
Business Research        Methods.
CSS Bookshops Limited.
Aina, L.O. (2004). Library and Information Science Text for Africa.
Ibadan: Third World         Services
Akinade, E.A. & Owolabi, T. (2009). Research Methods: A Pragmatic
Approach for Social         Sciences,
Behavioural Sciences and Education.
Lagos: Connel Publications.
Avwokeni, J.A. (2006). Research Methods: Process, Evaluation & Critique.
Portharcourt:         Unicampus
Tutorial Services.
Popoola, S.O. (2011, September). Research
Methodologies in Library and Information Science.

       A paper presented at a training
workshop on building research capacity for Library and
       Information Science professionals.
Organized by the Nigerian Library Association, Ogun
       State Chapter, held at Covenant
University, Ota, Nigeria on 18th – 22nd September, 2011.



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