Diagnostic testing

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Diagnostic testing

The assessment is the process of evaluating the student's knowledge and understanding in a specific domain in addition to know how efficient the teachers teach. Teachers themselves use the feedback out of assessment to revise teaching methods being used and develop further instruction. In literature, the importance of assessment sometimes represented as the purpose. Apart from that, the purpose of assessment is centred about two main things:

1. Evaluating students' achievement or learning.

2. Providing more effective instruction.

Mainly, assessment can be categorized into three types; Formative assessment, Summative assessment and Diagnostic assessment. I describe each in very brief. Formative assessment is part of the instructional process which occurs regularly throughout a unit or a course of study. On the other hand, summative assessment usually occurs at the end of a unit or course of study as an exam. The third type, which is our concern, is Diagnostic assessment which happens before studying process. In this article, I just focus the attention on the diagnostic assessment, its concept, importance and other issues.

Many learners have higher-level skills in some areas than in others. Thus, a diagnostic test is a test that is usually given to measure skills, abilities, knowledge, or some other factors to determine what students already know about a topic before it is taught. It is very important to determine a learner's strengths, weaknesses, and skills as well as determining areas where a learner is lacking and spend more time where necessary. Diagnostic assessment can be given whether to individual learner or a group of learners. The later is helpful since it tells the teacher that there is a lack suffer all group in particular topic. Thus, teacher in turn will spend more time to clarify misunderstood and ambiguous concepts.

Couple of researches addressed the diagnostic assessment in different shapes. It is used in primary school to identify a student learning needs, identify students' skills in writing. Treagust et al presented and describes steps for developing a diagnostic test of students' misconceptions in chemistry. Moreover, diagnostic assessment is used as with disabled student which has a difficulty in reading and writing. From all that, we see the diagnostic assessment is applicable to be used in whatever subject.

I turn the reader's attention to one of the most important points of this kind of assessment which is how to write a good diagnostic test. Good assessment construction means good preparation and vision, thus high quality assessment preparation process may take up to 20 weeks. Designing and constructing an assessment goes through multiple steps:

* Content Analysis: Which content is supposed to be covered in the curriculum? Are there significant sections of this content?

* Item writing: A question represents a specific objective derived from skill need to be mastered.

* Item review: Is the task clear in each item? Are the items expressed in the simplest possible language? etc.

* Planning item scoring: Is it based on objective questions?

* Trial of the items: Aims to improve the quality of the test.

* Production of the test.

We also should take care of test validity and reliability. The first means that the does the test measures what it claims to measure? On the other hand, reliability refers to the test consistency and stability. Finally, the diagnostic assessment, i.e. testing, plays important roll to determine the learner prior knowledge in such subject. As consequence, time and effort for both learner and teacher will be distinctly saved.


Fuchs, L. S., Fuchs, D., Hosp, M. K., & Hamlett, C. L. The potential for diagnostic analysis within curriculum-based measurement

Formative assessment and science education By Beverley Bell, B. Cowie

Assessment and Learning Guidance Booklets (www.sflip.org.uk)

Purposes and principles of assessment, Chris Rust