Developing a Reliable and Valid Measurement Instrument for Psychological Research

TESTS AND MEASUREMENTS
PART - 1
A PSYCHOLOGICAL CONSTRUCT

OVERVIEW
The presentation of this research paper has been done with a purpose of describing a process which would be
suitable for developing a reliable and valid measurement instrument which can be used in the psychological
research field. There have been instances when a researcher is not able to find an adequate or appropriate
scale for measuring an important construct. Under these circumstances, it becomes necessary to evolve a new
scale as the failure to develop a measurement instrument can result in invalid data. In order to build-up this
new measurement instrument, we need to understand some of the terminologies which are to be used for this
construct.
Measurement
Measurement, in a construct, is the process of recording the observations which are collected as part of the
research. There are two issues which need to be considered. The two major measurement concepts of
measuring are Levels of Measurement and Reliability of Measurement. Under Levels we have four major
segments: nominal, ordinal, interval and ratio. Under Reliability we include consideration and estimators
related to the true score theory.
We also need to understand the various types of measures which a researcher may use in social research. We
shall only consider four broad categories of measurements.
1. Survey Research includes designing and implementing interviews and questionnaires.
2. Scaling involves certain methods of developing and implementing the scale.
3. Qualitative Research involves an overview of non-numerical measurement methods.
4. Unobtrusive measures include different measurement methods which do not interfere with the research’s
context.

OVERVIEW
In this research paper we will adopt and work on developing a method based on Scaling. In a research process,
Scaling consists of a measurement method which involves the making of a construct which includes both
qualitative constructs and quantitative metric units. Scaling has found extensive use in the field of psychology
education for measuring the ‘unmeasurable’ constructs such as authoritarianism and self-esteem.
In Scaling, we make use of four scales of measurement: nominal, ordinal, interval and ratio. Basically, these are
just ways of categorizing variables of different type. Quantitative metric units, also referred to as numerical data,
are used where the observations are countable or measureable. In this context, we place 'Age' and 'income' as
continuous numeric variables. An 'age group' is considered as an ordinal qualitative variable and 'sex' is placed
under nominal qualitative variables.
Ordinal Measure
In ordinal measure, the interval between the values cannot be interpreted. However, in interval measurement,
the interval between two attributes can be interpreted. Let us take an example of measuring the temperature.
Here, the interval of 10 Units between 30 & 40 is the same as interval of 10 Units between 70 & 80. Here, the
interval between two values can be interpreted.
Ordinal Scale
This is a scale where data is placed just in order of its magnitude and there is no method or standard of
measuring the intervals between two quantities. As an example, consider the game of squash ladder which is
measured on an ordinal scale and from the results we can say that one person is better than the other, but we
cannot quantify the margin.

PART – 1: SCALE DEVELOPMENT AND
ANALYSIS
The purpose of this paper is to describe a process for developing a construct using multi-item, multi-subscale and
interval-level scales. The essential seven steps necessary for producing a reliable and user-friendly scales have been
followed.
The seven sections discussed hereunder cover the seven steps of a scale development. The process of scale
development begins with the first step which is creation of items for assessing the construct under consideration.
This step can be constructed either by allowing the process to be conducted inductively, where the items are
generated first and then the scales are derived; OR by allowing the process to be conducted deductively, where the
theoretical definition is created first and then the items are generated.
Step 1. Item Generation
The process of Deductive Scale Development is based on the theoretical definition of a construct and this has been
used as a guide to create the items. This approach is based on an understanding of the relevant theory of the case
study, of the phenomenon which is to be investigated and helps the researcher in ensuring that there is content
adequacy in the final scale constructs. This case study also provides a good example of the deductive approach to
be followed for item development as it also creates a measure for lodging quality.