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Abstract: This
article aimed to offer students and
researchers how to analyze
validity and reliability of their questionnaire as the instrument of research
or any other evaluation purposes. Analyzing
validity and reliability of questionnaire is really important to make sure that
the questionnaire is compatible and credible to be the instrument. The basis of
this writing was based on a mini-research with qualitative method. The subject
of research was the students of English Department who have written their
proposal and have conducted examination of their thesis. The sources of the
data were from observation and interview. The result was found
that many students did not know well about how to analyze the validity and
reliability of the questionnaire; they also did not know the significance of the
analysis; as well as they did
not know how to determine the appropriate technique and formula of the
analysis. Therefore, in this paper, it is offered how to analyze the validity
and reliability of Likert scale questionnaire. The popular technique of validity analysis is using
item analysis with correlation formula, and the reliability is using Cronbach Alpha
formula. The formulas are considered based on the types of data collection.

 

Keywords:
validity, reliability, instrument, questionnaire, research, evaluation

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1.   
Introduction

Evaluation and research are the two important issues
in education. In evaluation and research, there are various instruments those
can be used to get data; one of them is questionnaire. Questionnaire is a
series of written questions that should be answered by respondents in order to
get necessary information. Nigel, Fox, & Hunn (2009)
explained that questionnaire is as a tool of data collection on a research that
is often used in survey. Many types of questionnaires, but in this discussion
the writer only focuses on the popular and easy one; it is Likert scale
questionnaire. Likert scale questionnaire is a questionnaire where the form of
the data is ordinal (Norman, 2010).

Although the questionnaire is possible to be used, the
questionnaire is not really popular and familiar to be the instrument of
classroom assessment/ evaluation; test is the popular one; especially written
test. The questionnaire is very popular in a research. It is often used for
survey both qualitative and quantitative research. Such as Bird (2009)
mentioned that questionnaires are popular and fundamental tools for
acquiring information on public knowledge and perception.

As usual, instrument of a research (both
test and questionnaire) should be valid and reliable. So, in this case valid
and reliable questionnaire is a must. Valid questionnaire means that the
questionnaire can function as an instrument to measure what it is intended to
measure. This refers to some researchers’ statements talking about the term
validity such as Hughes (2003, p. 26) stated if a
test is said valid if it measures accurately what it is intended to measure. Also Rajhy (2014) stated that validity refers to the extent to
which the test measures what it says it measures. In line with those writers, Sugianto (2017) wrote validity is the extent to which
the test measures what it wants
to measure. Hamzah & Abdullah (2011)
wrote that the validity of test in the context of
testing the performance of students refers to the compatibility of the
aim of test with the contents of test. In
other words, a valid test can really measure what it is supposed to measure. So it can be concluded that validity of
questionnaire refers
to the suitability between a questionnaire as
an instrument of research and
the domain of what it is supposed to investigate
or measure.

The
extent of validity can be analyzed logically, empirically,
and item-based validity (Sugianto, 2017). For a research, it is popular to analyze the validity
of questionnaire based on items of the questionnaire. (Sugianto, 2016b) in his
paper talking about item validity stated that item validity meant
the accuracy of each item to measure what it supposed to measure; and the analysis is done by correlating the scores of each item to the total score. So the
technique of item analysis between a test and questionnaire is the same; it is
by correlation.

Reliable
questionnaire means that the questionnaire shows its credibility to be the
instrument of data collection. In a research, reliability level checking is the
second consideration to prove that the instrument is proper as the instrument
of the research. In term of test and it can be applied for term of
questionnaire, Sugianto (2017) explained
that reliability
refers to the consistency of scores, so it means a test would be considered as a
good test and credible as a measurement of learning achievement if the
result/score of test is consistent in how many times the test conducted. Brown (2005, p. 175) also
showed that
reliability is defined as the extent to which the result can be considered
consistent or stable. Then
Rajhy (2014) stated
that the results of test should be consistent where they remain stable and the
test should not produce different results when it is used in different days. So,
a questionnaire is considered reliable if the scores are approximately the same repeatedly. For the Likert scale questionnaire, since
the score is gotten from scale (ordinal number) there is a popular technique
and formula that can be used; it is Cronbach alpha. Alpha was developed
by Lee Cronbach in 1951 to provide a measure of the internal consistency of a test or scale (Tavakol & Dennick, 2011). Now it is popular to be called Cronbach alpha. Taber (2017) said that Cronbach’s alpha is a statistic commonly quoted by authors to
demonstrate that tests and scales that have been constructed or adopted for research
projects are fit for purpose. Cronbach alpha is popular in a research
to be used to see the reliability of questionnaire and essay test.

This paper was inspired based on the writer’s
experience become advisor of thesis writing where many students did not know
well how to determine the instrument of their research; they did not know the
function of try out; they did not know well how to see the validity and reliability
of their instrument either for test or questionnaire; they did not know how to
determine the appropriate and correct technique and formula of the validity and
reliability analysis of their instrument; and so on. So, in this paper the
writer needs to answer some questions; they are: 1) How are the knowledge of
students related to validity, reliability, and questionnaire? 2) How to analyze
the validity and reliability of questionnaire in appropriate way?

The objectives of this writing are to offer students
and researchers how to analyze validity and reliability of their questionnaire
as the instrument of research. The significance is that as reference for the
students and researchers so they are able to determine the appropriate and easy
technique and formula to analyze the validity and reliability of the
questionnaire.

Drost (2011) actually had offered generally about
technique and formula those could be used to see the extent of validity and
reliability, but there was no discussion about types of data as the basis of
technique and formula used. His discussion was in general and not specifically
mentioned about questionnaire matter.

In previous research and paper, actually the writer
had a research related to validity and reliability of instrument such as Sugianto (2011) that discussed about validity and reliability
of formative test, Sugianto (2016a) that discussed about validity and reliability
of English National Final Examination test, and also Sugianto (2017) that discussed about validity and reliability
of summative test. All the researches above are only all about instruments in
form of test for classroom matter. So there are no discussions related to
analysis for instrument of research matter. However, actually the procedures
are applicable for research matter as long as the form of the instrument is
also test like the test analyzed. Another previous writing is Sugianto (2016b) which discussed about the technique and
procedure of item analysis of objective test. This paper is type of item
analysis but special about objective test. The technique and procedure are
applicable for classroom matter test and research matter test/ instrument.

 

2.   
Methodology

As written in the introduction
that the students still have problem in their research related to their
instrument, to help the students’ problem the writer conducted this
mini-research. The methodology in this mini research was conducted in order to
know the fact exactly their condition or knowledge especially about their
ability in analyzing the questionnaire in terms of validity and reliability. Therefore,
in collecting the data the writer used observation and interview as the
instrument. The subject of study is some students of English Department of
State Islamic Institute of Palangka Raya Indonesia who have written their proposal of thesis writing and have conducted
examination of their thesis. The data were
analyzed qualitatively.

After knowing the condition or knowledge of students
related to their ability and knowledge about instrumentation of research, the
writer would elaborate how to analyze the validity and reliability of the
questionnaire especially Likert scale questionnaire.

 

3.   
Finding and Discussion

As stated in
introduction, actually the writer got the overview of students from the
writer’s experience became advisor of thesis writing. Then it was investigated
more by using procedure as stated in the methodology to find the real facts. From
the observation when the thesis examination and interview to some students, it
was found that although almost all of
them know what questionnaire is, but they did not know well how to see or
analyze the validity and reliability of the questionnaire; they did not know
the significance of analyzing validity and reliability of the questionnaire as
an instrument; as well as they did not know how to determine the appropriate
technique and formula of the validity and reliability analysis of the
questionnaire.

Based on the finding above it was needed to elaborate
the procedure, technique and formula to analyze the validity and reliability of
the questionnaire. The elaborations are in the following discussion.

 

3.1.  Validity of
Questionnaire

The easiest procedure to analyze the validity of
questionnaire is based on items. Every item of questionnaire is analyzed to see
the validity of each item. The technique is by correlating the score of item to
the total score. So, it would use correlation formula. The popular one is
Product Moment correlation or also mentioned as Pearson Product Moment.

Determining Product Moment correlation is
actually based on the types of data. Actually there are some types of
correlation formula such as Pearson
correlation (Product Moment, Point-Biserial, etc.), Kendall rank correlation, and
Spearman rank
correlation. Types of data influence the types of
correlation formula that is appropriate to be used. Sugianto (2016b) wrote that the appropriate formula in analyzing the
data related closely to the types of data. For example if the data those would be correlated are continuous data/
variables (ordinal, interval, and ratio), the appropriate formula is Product
Moment correlation formula. But if one of the data is nominal (dichotomous),
Point-Biserial correlation formula is the best one (Brown, 2005). Hamzah & Abdullah (2011) also discussed about the concept of the relation about types of data to
the statistical measurement.

Especially for questionnaire, based on the types of data those would be
correlated which are continuous data, so it would be Product Moment correlation
formula. Product Moment formula can be calculate manually by following the formula and can also be
processed by computer software such as Microsoft Excel and SPPS. The formula is actually as follow:

 

Where:

N              : number of pairs of
scores

        :
sum of the products of paired scores

           :
sum of X scores

           :
sum of Y scores

         :
sum of squared X scores

         :
sum of squared Y scores

 

Interpretation of coefficient could consult to r-table. If the
coefficient r of the item is equal or more than the value of r-table (r ?
r-table), it means the item is valid. But if the coefficient r of
the item is less than the value of r-table (r

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