By Japheth A. Yaya

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 These are published and unpublished sources e.g. journals, textbooks, newspapers, magazines, fliers, annual reports, bulletins, periodicals etc As a result, the kind of data to be collected, the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 respondents:

  • 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 dissertations.
  • Anecdotal records kept by teachers or counselors or researchers.

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.

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 inquiry.
  • 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, 2009:97).
  • 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 gathering.   Measurement Instrument

  • 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 handled. Measurement Instrument

Table1: Classification of Research Based on Data Collection Instruments

S/NTypes of ResearchData Collection Instruments
1.AppliedQuestionnaire, Interview and observation.
2.SurveyQuestionnaire, focus group discussion, interview and observation.
3.Case studyQuestionnaire, interview, focus group discussion and observation.
4.Ethnographic e.g. correlational researchObservation, questionnaire, focus group discussion and interview
5.HistoricalObservation, focus group discussion and interview
6.EvaluationFocus group discussion, interview and observation
7.Pure scienceExperiment and observation
8.ActionQuestionnaire and interview
9.LongitudinalQuestionnaire, observation, focus group discussion, interview and experiment in case of pure science research.
10.ExploratoryQuestionnaire, observation and interview.

Source: Japheth Yaya, 18th June, 2016


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. Measurement Instrument


Adedokun, J.A. (2003). Basics of Research Methodology. Sagamu: New Hope Publisher. Measurement Instrument
Adeniyi, A.L.; Oyekanmi, A.O. & Tijani, M.O. (2011). Essentials of Business Research        Methods. Lagos: CSS Bookshops Limited.
Aina, L.O. (2004). Library and Information Science Text for Africa. Ibadan: Third World         Services Limited.
Akinade, E.A. & Owolabi, T. (2009). Research Methods: A Pragmatic Approach for Social         Sciences, Behavioural Sciences and Education. Lagos: Connel Publications. Measurement Instrument
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. Measurement Instrument


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